Kilobaud 1980 01

In This Issue — 27 Articles

^ ^. = Including:

Dial-CJp Directory: New Series on CBBS Activity 26

Operator-Oriented Data Base Management— Part 1 84

^__ o Customized PET ! Computer and Disk Drives in a Single Package 116

T - OSI Challenger 1 P MF Review 140

Complete Table of Contents on naae 5.

o

Fpcm PEflGCM

One-Drive System:

$399. (40-track) & $675. (77-track)

Two-Drive System:

$795. (40-track drives) & $1350. (77-track drives)
Three-Drive System:

$1195. (40-track drives) & $2025. (77-track drives)
Requires Expansion Interface, Level II BASIC & 16K RAM.

Low Cost Add-On Storage for Your TRS-80*.

In the Size You Want.

When you’re ready for add-on disk storage, we’re ready for you.
Ready with six mini-disk storage systems — 102K bytes to 591 K bytes of

additional on-line storage for your TRS-80*.

• Choose either 40-track TFD-100™ drives
or 77-track TFD-200™ drives.

• One-, two- and three-drive systems im-
mediately available.

• Systems include Percom PATCH PAK
#1™, on disk, at no extra charge. PATCH
PAK ^1™ de-glitches and upgrades
TRSDOS* for 40- and 77-track operation.

• TFD-100™ drives accommodate “flippy
disks.” Store 205K bytes per mini-disk.

• Low prices. A single-drive TFD-100™
costs just $399. Price includes PATCH
PAK #1™ disk.

• Enclosures are finished in system-
compatible “Tandy-silver” enamel.

Whether you need a single, 40-
track TFD-1 00™ add-on or a three-drive
add-on with 77-track TFD-200™s, you
get more data storage for less money
from Percom.

Our TFD-100™ drive, for example,
lets you store 102.4K bytes of data on
one side of a disk — compared to 80K
bytes on a TRS-80* mini-disk drive —
and 1 02.4K bytes on the other side, too.
Something you can’t do with a TRS-80*
drive. That’s almost 205K bytes per
mini-disk.

And the TFD-200™ drives provide
197K bytes of on-line storage per drive

— 1 97K, 394K and 591 K bytes for one-,
two and three-drive systems.

PATCH PAK #1™, our upgrade
program for your TRSDOS*, not only
extends TRSDOS* to accommodate 40-
and 77-track drives, it enhances
TRSDOS* in other ways as well. PATCH
PAK #1™ is supplied with each drive
system at no additional charge.

The reason you get more for less
from Percom is simple. Peripherals are
not a sideline at Percom. Selling disk
systems and other peripherals is our
main business — the reason you get
more engineering, more reliability and
more back up support for less money.

In the Product Development Queue . . . a printer interface for using your TRS-80* with any
serial printer, and . . . \he Electric Crayon™ to map your computer memory onto your color TV
screen — for games, animated shows, business displays, graphs, etc. Coming PDQ!

™ TFD-100, TFD-200. PATCH PAK and Electric Crayon are trademarks of PERCOM DATA COMPANY.

‘TRS-80 and TRSDOS are trademarks ot Tandy Corporation and Radio Shack which have no relationship to PERCOM DATA COMPANY.

I PEBQCM 1

V

PERCOM DATA COMPANY, INC.
211 N. KIRBY • GARLAND, TX. • 75042

To order add-on mini-disk storage for your TRS-80*,
or request additional literature, call Percom’s toll-free
number: 1-800-527-1592. For detailed Technical infor-
mation call (214) 272-3421.

Orders may be paid by check or money order, or
charged to Visa or Master Charge credit accounts. Texas
residents must add 5% sales tax.

Percom ‘peripherals for personal computing’

22 INTETCC DATA SYSTEMS

SuperBrain

The Honor Graduate

There’s been a lot of talk lately
about intelligent terminals with
small systems capability. And, it’s
always the same. The systems
which make the grade in perfor-
mance usually flunk the test in
price. At least that was the case
until the SuperBrain graduated with
the highest PPR (Price/ Perfor-
mance Ratio) in the history of the
industry.

For less than $3,000*, SuperBrain
users get exceptional performance
for just a fraction of what they’d
expect to pay. Standard features in-
clude: two dual-density mini-flop-
pies with 320K bytes of disk storage,
up to 64K of RAM to handle even
the most sophisticated programs,
a CP/M Disk Operating System
with a high-powered text editor, as-

*Quantity one. Dealer inquiries invited.

sembler and debugger. And, with
SuperBrain’s S-100 bus adapter, you
can even add a 10 megabyte disk!

More than an intelligent terminal,
the SuperBrain outperforms many
other systems costing three to five
times as much. Endowed with a
hefty amount of available software
(BASIC, FORTRAN, COBOL), the
SuperBrain is ready to take on your
toughest assignment. You name it!
General Ledger, Accounts Receiv-
able, Payroll, Inventory or Word Pro-
cessing . . . the SuperBrain handles
all of them with ease.

Your operators will praise the
SuperBrain’s good looks. A full
ASCII keyboard with a numeric key-
pad and function keys. A non-glare,
dynamically focused, twelve inch
screen. All in an attractive desktop
unit weighing less than a standard

office typewriter. Sophisticated
users will acclaim SuperBrain’s twin
Z-80 processors which transfer data
to the screen at 38 kilobaud! Inter-
facing a printer or modem is no
problem using SuperBrain’s RS-
232C communications port. But best
of all, you won’t need a PhD in com-
puter repair to maintain the Super-
Brain. Its single board design makes
servicing a snap!

So don’t be fooled by all the fresh-
man students in the small systems
business. Insist on this year’s honor
graduate . . . the SuperBrain.

5INTE3TEC

DATA

= SYSTEMS.

2300 Broad River Road, Columbia, SC 29210
(803) 798-9100 TWX: 810-666-2115

MORE CAPABILITIES THAN
ANY OTHER PERSONAL COMPUTER

UNDER $1,000*

Compare the built-in features of the
ATARI' 8 ' 80(Twith other leading personal
computers. Whether you program it
yourself or use pre-programmed car-
tridges or cassettes, the ATARI 800 gives
you more for your money.

Run your own programs? Easy. Just
plug in the 8K BASIC or optional
Assembler language cartridge, and
go. They're ROM based. That means
more RAM for your programs.

Also included with the ATARI 800 is
an internal speaker and four separate
sound channels, FCC approval, a
built-in RF modulator, the ATARI 410“
Program Recorder and a high speed

A high-speed printer. And more to come.

Graphics programs? No problem. The
ATARI 800 offers 128 color variations:

16 colors in 8 luminance levels. Plus
29 keystroke graphics symbols and 8
graphics modes. All controlled from a
57 character ASCII keyboard. With upper
and lowercase.

Or, program it our way.There are excit-
ing programs available and many more
on the way for the ATARI 800. Business
programs. Home Management pro-
grams. Entertainment. And with the 410
audio/digital recorder, you can add
Atari's unique Talk & Teach“ Educational
System cassettes.

Your way or our way, you'll find that
the ATARI 800 is probably the most
powerful computer that $999.99*
can buy.

And with that power, you get depend-
ability. Dependability built into Atari's
custom designed and fully-tested LSI cir-
cuitry and lower component count, (less
components, less chance for failure).

But if anything ever does go wrong,
you'll find a complete network of
computer-connected Atari service facil-
ities waiting for you throughout the
country.

Make your own comparison. Hands
on. Anywhere computers are sold. Or,

serial I/O.

Peripherals? Add up to 48K of
user installable RAM. Or up to four
individually accessible floppies.

send for a free chart that compares
the features of the ATARI 800 to
other leading fully-programmable
computers.

'Suggested retail price $999.99, includes
computer console, program recorder
and BASIC language cartridge.

PERSONAL COMPUTER SYSTEMS

1 265 Borregas Ave., Dept. C, Sunnyvale, California 94086. Call toll-free 800-538-8547
(In California 800-672-1404) for the name of your nearest Atari retailer.

©Atari 1979

O Warner Communications Company

kilobaud

MICROCOMPUTING"

contend jan. ’80

ARTICLES

26 Dial-up Directory Start of a series on computer bulletin board services. Frank J. Derfler, Jr.
28 Tiny Dual-Trace Oscilloscope Non-Linear Systems’ Model MS215. Nat Wadsworth
32 Chinese Character Generation Use the Sorcerer’s graphics keys. Timothy Huang
36 Using Five-Level Teleprinters with a TRS-80 These printers abound. Brian Bateman
50 A Video Board from Ithaca Intersystems This article takes a look at it. Ernie Brooner
52 Route 66 Modem Exchange information with this economical design. Frank J. Derfler, Jr.

56 The SWTP Computer System Installment number 8 looks at the 6809. Peter A. Stark

micro info

TT This symbol next to a title in
the table of contents indicates
that the article is a business-
application article.

Manuscripts

Contributions in the form of manu-
scripts with drawings and/or photo-
graphs are welcome and will be con-
sidered for possible publication. We
can assume no responsibility for loss
or damage to any material. Please
enclose a self-addressed, stamped
envelope with each submission. Pay-
ment for the use of any unsolicited
material will be made upon accep-
tance. All contributions should be di-
rected to the Microcomputing
editorial offices. "How to Write for
Microcomputing" guidelines are
available upon request.

Editorial Offices:

Pine Street

Peterborough NH 03458
Phone: 603-924-3873, 924-3874

66 Outer Limits Addition Overcome programming limitations. Allan S. Joffe
70 TM990/189 University Board New microprocessor from Texas Instruments. John Caulfield

74 Not-So-Fast Renumberer for OSI BASIC For neat and tidy listings. John W. Aughey

Advertising Offices:

Pine Street

Peterborough NH 03458
Phone: 603-924-7138, 924-7139

78 Visions of Sacks of Silver Dollars Blackjack-strategy tutor. Thomas W. Glaser

84 $. Data Base Management System First in 3-part series describes the system. Joel Shapiro

90 Relocator for North Star BASIC Find all the applications. Lance E. Rose

Circulation Offices:

Pine Street

Peterborough NH 03458
Phone: 603-924-7296

94 Synertek’s SYM-1 The newly named VIM is still versatile. Bonaventura Paturzo

98 Converting Selectric Keyboards from BCD to Correspondence Code (part 2). Robert m. wen

To subscribe, renew
or change an address:

102 Plucking Programs from Thin Air An unusual source of programs. John J. Glidewell

110 “Core” and More for Your Apple Accessories for serious computing. Leslie R. Schmeltz

116 The Metamorphosis of a “Custom” PET Portability in a disk-based PET. Robert Freeman

126 Darkroom Master Unleash your PET in the darkroom. Jeff Knapp

134 TRS-80 Printer Interfaces Serial and parallel designs. Rod Hallen

140 The OSI Challenger IP MF A good minifloppy for the beginner. Charles Curley

Write to Microcomputing, Subscrip-
tion Department, PO Box 997, Farm-
ingdale NY 11737. For renewals and
changes of address, include the ad-
dress label from your most recent
issue of Microcomputing. For gift
subscriptions, include your name and
address as well as those of gift recip-
ients. Postmaster: Send form #3579
to Microcomputing, Subscription Ser-
vices, PO Box 997, Farmingdale NY
11737.

144 A Heath H8 Disassembler a foiiow-up to "CONOPS." chesney e. Twombiy

150 Software Clock for the 6800 Instant access to correct date and time— in ASCII. Richard R. Parry

160 Converting a Bargain TV to a Video Monitor Use the Lancaster method. Stephen E. Bach
164 Load Your SWTP at 4800 + Baud With JPC Products’ cassette interface. Jerry L. Hunt
172 Hex and ASCII Do it with an ASCII keyboard. D. E. Price

Subscription
problem or question:

Write to Microcomputing, Subscrip-
tion Department, PO Box 997, Farm-
ingdale NY 11737. Please include an
address label.

180 Interrupting BASIC You’ll need a source listing and this article. Willits, Wiser

DEPARTMENTS

Publisher’s Remarks -6

Output from Instant Software, Inc. -7

Books -8

PET-pourri — 14

Computer Clinic - 16

Club Notes -16

Letters -17
New Products -20
Classifieds - 170
Corrections -170
Dealer Directory- 171
New Software - 188

Coven This month’s cover shows CBBS Boston (617-963-8310) dialed up and displayed on a Heath H19. (Photo by Reese
Fowler, ISI staff)

Kilobaud Microcomputing (ISSN
0192-4575) is published monthly by
1001001, Inc., Pine St., Peterborough
NH 03458. Subscription rates in U.S.
are $18 for one year and $45 for three
years. In Canada: $20 for one year and
$51 for three years. In Europe, send
89, -DM in Eurocheque or send credit
card information to: Monika Nedela,
Markstr. 3, D-7778 Markdorf, W. Ger-
many. South African Distributor: KB
Microcomputing, PO Box 782815,
Sandton, South Africa 2146. Austra-
lia: For subscriptions write-
Katherine Thirkell, Sontron Instru-
ments, 17 Arawatta St., Carnegie, Vic.
3163 Australia. All other foreign sub-
scriptions are $23 -one year only
(surface mail). Second-class postage
paid at Peterborough NH 03458 and at
additional mailing offices. Phone:
603-924-3873. Entire contents copy-
right 1979 by 1001001, Inc. No part of
this publication may be reprinted or
otherwise reproduced without written
permission from the publisher.

Microcomputing January 1980 5

Wayne Green

PUBLISHER’S REMARKS

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^/US-He-UI
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tio Id] B# 571

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.1!®; I JH It tX tt
iH H 71 S 5X I'fc
SHi*lBj*

It takes an 18 by 22 dot matrix to
print these Chinese characters. It
takes a lot of time to put the
characters together and a long
time to print them. That the
Chinese have been able to cope
with their incredible written
language with computers is a
testimony to man's ability to
adapt to almost anything.

Next Year: Asia!

Well, you missed out on a big
one. The IEEE sponsored a trip
to Asia in October. It was a hum-
dinger. Over 100 people went to
consumer electronics shows in
Seoul, Osaka, Teipei and Hong
Kong. Some went to look for
products to sell. Some went with
products to be sold in these rapid-
ly growing markets. Some went
for the fun of it. No one was dis-
appointed.

The trip, which at well under
$2000 for three weeks in several
countries was one of the modern-
day bargains, included all
transportation, hotels and more
meals than you might want.

If you sell anything, the cornu-
copia of products on display at
these consumer electronics shows
will fire your imagination. And if
they don’t already have what you
want, you can bet that they will
be happy to gear up and produce
what you need in a few days.

Korea and Taiwan, in particu-
lar, are almost desperate for trade
and are ready to buy your prod-
ucts or make them for you . . .
with government assistance. If
you have anything that might sell
in China, go to Hong Kong, the
great entryway to China.

Sherry and I are planning to
take this tour again next year, and
I hope that some of you will join
us in the fun. We’ll set up visits to
computer stores and manufactur-
ers and talk with computer clubs.

I’ll have more information on

this trip in 1980; for now, mark
off the first three weeks of Oc-
tober and plan to do some fan-
tastic traveling during this time.

China Has a Big Problem

My recent visit to both Taiwan
(Republic of China) and Hong
Kong (essentially an adjunct to
mainland China) put me in touch
with the latest Chinese micro-
computer technology. The
Chinese have a problem. Their
language is incompatible with
computers.

I watched two different
Chinese character-generator ter-
minals at work. One had hun-
dreds of keys, each with up to five
different characters on it, and
many characters required the use
of two or more keys. This system
could generate 10,000 different
characters ... a sort of
minimum for writing in the
language. Another had a system
that built up the characters with
as many as seven parts before dis-
playing the complete character
. . . again with a 10,000-char-
acter library.

The basic problem is that each
Chinese character is like one of
our words, and the Chinese have
no phonetic spelling system. The
Japanese do have a phonetic sys-
tem, called Kana, so they are able
to cope with computers. I under-
stand that Singapore, which is 98
percent Chinese, has decreed that
the official language of the coun-

try will be English within 20
years. It is a little late to invent a
Chinese phonetic language, so
perhaps the writing of thousands
of years should be set aside and
English selected for China for the
future. This would not be easy.

As China falls behind the rest
of the world in computer use, I
think the pressure will be on for
some solution to the problem.
Microcomputers will quickly ag-
gravate this problem by making
even small businesses and educa-
tion dependent on computers.
The Chinese are good business-
men, so I think they will see the
poster on the wall and realize that
something is going to have to
give. As deeply as they are rooted
in tradition, tradition will have to
give way to technology if China is
going to be competitive in the
future.

Few people are yet aware of the
incredible changes that micro-
computers are going to make in
the world. Those who see what is
happening realize that the world
will never be the same. In high-
technology countries, computers
will make it possible for people to
be freed from repetitive tasks
such as secretarial work, filing
and record keeping. Emerging
nations will depend on micro-
computers for business and
education as much as high-tech-
nology countries.

Where does this leave a country
with no phonetic language? A
simple and computer-compatible
language is required to cope with
the coming changes. Thus I think

Many of the keys have up to five different characters or character com-
ponents, which can be put together with others to make the finished
Chinese characters. The 10,000 characters that can be generated with
this system constitute a minimum language, since most Chinese use
four to eight times that number of characters when writing.

This Chinese character generator has over 200 keys used to build up a
library of over 10,000 different characters.

6 Microcomputing January 1980

that China will have to grit its col-
lective teeth and opt for English
as a way to accommodate com-
puters.

Recognizing this situation, In-
stant Software is shipping pro-
grams in English to both Taiwan
and Hong Kong. The programs
being sent to Japan are in both
English and Kana. Those going to
Korea are largely being translated
into Korean.

Practice the Preaching

Can a magazine have too much
circulation? I think so, and I’ll

ISI Sales Reps

You’ll be reading more about
the developing Asian distribution
of Instant Software elsewhere,
but the nub of it is that software is
now being exported to Japan and
will eventually be available in
about 100 computer stores there
in both English and Japanese ver-
sions.

Meanwhile, distribution in the
U.S. has been stepped up. More
computer stores are joining the
Instant Software team; we are
projecting over 500 stores asso-
ciated with ISI by the end of
1979. Dozens of enthusiastic peo-
ple have been applying for the
sales rep jobs, and a network of
reps is being established.

Because the key to the success
of any publisher lies primarily in
marketing, ISI has set up the first
rep organization in the micro-
computer field. These sales reps
go into every computer outlet and
make sure that the outlets are
aware of the benefits Instant
Software will bring.

ISI is also going into every
country in the world where
microcomputers are sold and
making sure that ISI program
packages are on hand to help
these sales. This brings Instant
Software to a world market of
well over 600 million people. We
have translators setting up our
programs in more languages and
supporting more systems.

We need more associate editors
to help convert our program
packages for the Apple and

tell you why. The main problem
when circulation increases is that
advertising costs also have to go
up by the same percentage. When
the ad rates go up, smaller firms
no longer can afford to run ads.
This not only discourages new
small firms, it also makes a maga-
zine less interesting. These new
firms often have the most pro-
gressive products and the best
bargains.

With Kilobaud Microcomput-
ing's circulation reaching
100,000, I faced a serious situa-
tion. Ad rates, which are based
on so many dollars per thousand
readers, would have to be in-
creased. One look at the adver-
tising barrenness of high-circula-

Heath systems. Some of the pro-
grams call for extensive graphics
conversions, which will be com-
pensated by increased royalties
for this work. If you have both a
TRS-80 and an Apple, this might
be a way to make a nice addition-
al income, one that will come in
every month in royalties. Write to
me about this.

As I look over the competition,
I believe that both our quantity
and quality are now tops in the
field. As a programmer, your
royalties are going to be a direct
function of the ability of your
publisher to sell, so the bigger the
firm you go with, the more sales
you can expect. The problem here
is that the competition for publi-
cation of a specific type of pro-
gram will be tougher with a large
publisher such as ISI, and you
could find yourself coming in sec-
ond to some other programmer.
There is much to be said for get-
ting busy— now— and not wait-
ing.

Smaller firms that have tried to
market program packages have
contacted us to simplify their
sales and distribution problems.
They have had difficulties with
credit, advertising, duplication,
packaging, printing documenta-
tion and unwillingness of many
dealers to try to do business with
a hundred small firms instead of
one large one. By letting ISI do
the marketing, smaller firms can
concentrate on writing and de-
veloping program packages rath-
er than involving themselves with
the endless miseries of marketing
and financing.

tion magazines convinced me that
I didn’t want to go that route.

The increase in sales and inter-
est in the TRS-80 system made it
obvious that TRS-80 information
would eventually push out the
coverage of other systems in Mi-
crocomputing. It was also obvi-
ous that this would quickly in-
crease the circulation of the mag-
azine to where it would start to
freeze out smaller firms. When I
started Byte my overall plan was
for us to build magazines up to a
maximum circulation of around
100,000 and then split them ac-
cording to separate interests to
keep down further growth. The
easiest split for Microcomputing
was to start 80 Microcomputing.

Warning

If you are a TRS-80 user and
have a CTR-80 cassette recorder,
be sure to have Radio Shack do a
free fix on your recorder so it will
not zap your program tapes. We
get back a few tapes each month
that have been zapped this way,
and we replace them for a $1 ser-
vice charge. But this is a big pain
for any computerist, and the re-
corder should be modified so it
will not accidentally erase parts
of the program.

One hint: If you do manage to
ruin part of a program, check to
see if there is a second recording
of the program further on down
the tape. Most ISI program cas-
settes have two dumps of the pro-
gram ... just in case one gets
botched in some way.

Questions and Answers

Some phone callers have
wondered why Instant Software
doesn’t answer questions that
have been written in. We do an-
swer, but many programmers in-
clude questions with submitted
programs. That’s a sure way to
not get answers. If there are ques-
tions, use a separate sheet of
paper and envelope so the ques-
tions won’t go into the program
files. Better, address questions to
Editor-in-Chief Paul Weiner, In
stant Software, Peterborough
NH 03458.

MICRO COM PUTING ™

PUBLISHER/EDITOR

Wayne Green

EXECUTIVE VICE PRESIDENT
Sherry Smythe
CORPORATE CONTROLLER
O. Alan Thulander
ASSISTANT PUBLISHER/EDITOR
Jeffrey D. DeTray
MANAGING EDITOR
John Barry

EDITORIAL ASSISTANTS

Dennis Brisson
Susan Gross

ADMINISTRATIVE ASSISTANT

Dotty Gibson

PRODUCTION DEPARTMENT
MANAGER:

Noel R. Self

ASSISTANT MANAGER:

Robin M. Sloan
STAFF:

Steve Baldwin
Robert Drew
James H. Gray II
Bruce Hedin
Carl Jackson
Ken Jackson
Dion Owens
Nancy Salmon
Patrice Scribner
John W. White

TYPESETTING

Barbara J. Latti
Sara Bedell
Rhonda Clapper
Sandie Gunseth
Mary Kinzel

PHOTOGRAPHY

W. H. Heydolph
Tedd Cluff
Terrie Anderson

PROJECTS EDITOR

Jim Perry
BOOK EDITORS

Peter Perin
Chris Brown
Emily A. Gibbs

ASSOCIATE EDITORS

Frank J. Derfler, Jr.

Rod Hallen
Peter Stark
Sherm Wantz

BOOKKEEPER

Knud E. M. Keller
MARKETING/CIRCULATION
Harold L. Stephens
Donna Taylor

BULK SALES MGR.

Judy Waterman
CIRCULATION
Pauline Johnstone
COMPUTER PROGRAMMING
Richard Dykema
EUROPEAN MARKETING DIR.

Reinhard Nedela
AUSTRALIAN DISTRIBUTOR
Katherine Thirkell

ADVERTISING

Aline Coutu, Mgr.

Marcia Stone
Penny Brooks
Nancy Ciampa
Cheryl McDaniel
Jerry Merrifield
Lori Mugford
Kevin Rushalko
Carol Symonowicz

OUTPUT FROM ISI

Sherry Smythe

Microcomputing January 1980 7

BOOK REVIEWS

Payroll with Cost
Accounting in CBASIC
Osborne/McGraw-Hill
Berkeley CA
Looseleaf with binding
364 pages, $15(?)

I indicated the price of the
book as “SI 5(?)” because I wrote
the review using an advance copy,
prior to publication of the book;
hence, I did not know what the
exact retail price would be.

The Osborne series of business-
program books forms an inte-
grated accounting system com-
posed of three parts: payroll with
cost accounting, accounts pay-
able/receivable and general led-
ger. Each part can be used inde-
pendently or in conjunction with
the others. In this respect the
Osborne system is similar to sev-
eral competing systems. It is dis-
similar in another respect: price.
The retail prices of comparable
products are typically in the $700
range, while the end-user cost for
one part of the Osborne system is
$15 for the book and another
$100 or so for a disk containing
the programs.

The first versions of the busi-
ness-program books used Wang
BASIC. The new versions — of
which Payroll is the first— use
CBASIC-2, which is widely avail-
able for 8080- and Z-80-based mi-
crocomputers. The CBASIC-2
versions are functionally identi-
cal to the Wang BASIC versions.
To run the programs under the
CP/M operating system and the
CBASIC-2 compiler, the micro-
computer system should have
40K memory, a video terminal
with programmable cursor con-
trol and a 132-column printer
with form-feed (or “top-of-
page”) control. Substantial disk
capacity should be available.

Simplicity is a key feature of
the books at the end-user level.
Functions are selected from a
menu that the programs display
on the video terminal. Payroll in-
cludes 34 primary functions,
ranging from file maintenance to
report generation. Eight of the
functions support the job cost ac-
counting subsystem. Each of the
34 functions is actually a separate
program or a separate set of pro-
grams. A controlling program—
the “menu” program— allows

the user to select a function from
the menu display; the program
for the selected function is then
loaded automatically from disk.

Payroll with Cost Accounting
—CBASIC (i.e., the book) is di-
vided into eight chapters. The
first provides an overview of the
system, followed by a list of avail-
able functions. Chapter two,
“Data Files,” explains the file-
accessing techniques used. It lists
and describes the data files the
payroll system maintains. This
chapter also includes two useful
tables: a cross-reference of which
programs use which files and a
detailed layout plan of the files.

Chapter three is the “Manage-
ment Guide.” It describes the
procedures normally required for
successful use of the system.
Some procedures are usually per-
formed daily, others monthly,
others quarterly and so on. Also
described in this chapter are tech-
niques to prevent and recover op-
erator errors.

Chapter four, the “User’s
Manual,” is a 150-page book-
within-a-book. Its half-dozen
pages of introductory material
are followed by detailed instruc-
tions for the 34 functions. Each
function receives several pages of
consideration, including textual
discussion, sample program dis-
plays and/or printouts and a user
flowchart. As with the other sec-
tions of the volume, the text of
the User’s Manual is consistently
lucid. General readability is im-
proved by a boldface/lightface
format that appears in many
other Osborne publications.

Chapter five describes the
hardware and software needed
for direct use of the CBASIC-2
versions. For those who plan to
convert the programs to another
dialect of BASIC— or even an-
other language— the chapter next
covers the elements of CBASIC-2
that are substantially different
from more conventional, inter-
preted BASICs. Chapter six,
“Changing This Payroll,” pro-
vides useful instructions on how
to customize the system.

Chapter seven covers miscel-
laneous information relating to
setup and maintenance of the
payroll system: details on com-
mon subroutines, disk space
mapping, data file creation and
CRT mask manipulation. The
latter represents a feature of the
Osborne systems: display masks

are defined centrally and may be
modified using a program called
CRTFM. The section on CRT
mask files is a bit cursory.

The final chapter contains the
source listings of the 39 programs
and ten common subroutines that
form Payroll. The listings are
large enough to read. They are
also amply commented with re-
mark statements. Another docu-
mentation aid is the frequent use
of descriptive variable names,
such as DEDUCTION. AMOUNT
and ANNUAL. PAY.

A small question arises: how
do you transfer 300K + of listings
from the printed page to a com-
puter? You could key them in,
perhaps, but that wouldn’t be
practical. The solution is to make
the programs available on disk,
which Osborne has done.

The company sells 8-inch, sin-
gle-density disks containing
source listings (.BAS suffix) of
the programs. The disks cost $250
per part; payroll, accounts
payable/receivable and general
ledger are three separate parts.
Purchasers of the disks may mod-
ify and copy them for resale with-
out royalty. That is, Osborne has
defined their copyright to pro-
hibit only human-readable (i.e.,
printed) reproductions of the
programs. (Presumably, you are
permitted to generate hard-copy
listings for local use, however.)

Other companies have con-
verted the programs to run on
other microcomputers and mini-
computers. Osborne maintains a
referral list for customers who
want to obtain conversions for
their systems. At this writing,
nearly 20 computers are sup-
ported by recognized converters.
Each converter determines his
own price.

The Osborne business-program
books seem ideal for the emerg-
ing micro-based business system
market. Even in comparison to
the few competent software pack-
ages available today, the Osborne
programs are good. And while
the books are intended for the im-
plementor who wants to use the
published programs, they also
form worthwhile models and ref-
erences for the programmer who
wants to develop his own business
software. In either case, the
Osborne series should prove in-
valuable.

David Price
Midlothian VA

BASIC with Style

Wagin and Ledgard
Hayden Book Co., Inc.

Rochelle Park NJ
1978, $5.95

BASIC with Style is one of a
series of “programming prov-
erbs” books. Other volumes have
been published for FORTRAN,
COBOL and ALGOL/PL/ 1. The
aim of all of the books in the
series is the same: to present and
explain a small set of nineteen
rules for writing well-structured
programs.

BASIC with Style assumes that
the reader knows the rules for
writing syntactically correct BA-
SIC programs. The point of the
book is to teach you how to go
from programs that follow the
rules of BASIC grammar to pro-
grams that are good from the
point of view of BASIC style.
Style does not mean attractive;
it means well thought out and
easy to read, check and modify
. . . top-down structured pro-
gramming.

Structured programming is
often presented as complicated
and executable only in special
languages (such as PASCAL or
ALGOL) that are not usually
available — especially on home
computers. True, it is easier to
write structured programs in
PASCAL, but it can be done in
BASIC almost as well. This book
shows how. The basic rules pre-
sented here are simple: think be-
fore you write, write in manage-
able chunks, comment as you go
and check your work. All this is
common sense; the book shows
how to apply it.

Only on two points do the au-
thors give advice that may not be
applicable to personal comput-
ing. The first is their heavy stress
on desk-checking syntax. This
may be important in a batch envi-
ronment where you wait half a
day between the time you submit
a program and the time you get it
back; in an interactive context, it
is much faster to run the program
and let your BASIC tell you when
you have mistyped something.
Computers are much better at
routine work than are people!

The second area where the
book departs from a personal-
computing context is in discuss-
ing the establishment of pro-

8 Microcomputing January 1980

gramming standards. This is
something a programming group
does; an individual can set and
modify his or her own practices as
experience dictates.

In conclusion, BASIC with
Style is a useful book for some-
one who has already learned BA-
SIC and who wants to learn how
to write programs according to
modern ideas of effective pro-
gramming. Programs written fol-
lowing the recommendations in
this book will be easier to write,
more likely to work and easier to
modify. They will also take up
more memory, but that is often a
small price to pay for a working
program.

John A. Lehman
Ann Arbor MI

The Elements of
Programming Style

Kernighan and Plauger
McGraw-Hill, New York, 1974
141 pages, softcover

If you intend to write programs
to be used by other people, then
you should read this book. If you
expect to become a professional
programmer, this book is manda-
tory reading.

The Elements of Programming
Style is definitely not an ordinary
“how to program” book. In my
opinion, there are three distinct
differences between this and most
programming books.

The first is Kernighan and
Plauger’s primary concern with
the “human factors” of pro-
gramming: how to write pro-
grams that are easier for people to
read, understand and use. The
authors make the point that if
enough attention is devoted to the
human requirements in pro-
grams, the machine requirements
will take care of themselves. To
paraphrase the conclusion of
chapter 1 : The problem with pro-
grams people have trouble under-
standing is not that computers
have similar trouble, but that the
programs often don’t do what
they are meant to do.

Addressing the problem of
having a program do what it is in-
tended to do, Kernighan and
Plauger present 63 “points of
style.” These range from the gen-
erally familiar — “parenthesize to
avoid ambiguity,” “make sure
comments and code agree,”
“choose a data representation
which makes the program sim-
ple,” “watch out for off-by-one
errors” — to the more esoteric —

“10.0 times 0.1 is hardly ever
1.0.” If any of these rules does
not seem obvious, don’t worry.
As you read the book, every rule
is derived from examples that
clearly show its application.

The second difference between
Elements of Programming Style
and other programming books is
the examples. Every example in
this book is a program (or pro-
gram segment) taken from a pub-
lished programming textbook.
Kernighan and Plauger then im-
prove these programs using the
points of style they wish to illus-
trate.

The authors mention two rea-
sons why they use published pro-
grams for their examples: (1) to
show the application of the
“points of style” to already exist-
ing programs rather than present
the reader with contrived exam-
ples and (2) to learn to write bet-
ter programs by improving old
programs.

This means learning to read
critically and to rewrite programs
carefully. These examples will
convince good-to-average pro-
grammers that this book is not
just a rehash of known informa-
tion. I can think of no better
book to teach the underlying
principles of program develop-
ment to beginning programmers.

The third difference about this
book is a different method of
publication. In their examples,
Kernighan and Plauger uncover
numerous errors, not just in style,
but obvious programming errors
such as typographical mistakes,
misspelled identifiers and trans-
posed statements that would have
made it impossible to run the pro-
gram as given. They also uncover
plenty of not-so-obvious errors
that should have been caught dur-
ing testing. In order not to have
the same kind of mistakes show
up in their book, the authors
typeset the book themselves, us-
ing a computer-driven typesetting
program that allowed them to test
the examples directly from the
text. While Kernighan and
Plauger make no claim that their
versions of the programs are
“best” in any sense, there is some
assurance that they will work as
presented.

Elements of Programming Style
provides convincing proof that
writing programs that are easy to
debug, work properly with no
hidden failure modes and are easy
to use does not have to be a black
art. Instead it is possible for any-
one who will learn and apply a
few basic principles of program-
ming style. The authors also prove
that it is possible to make these

“better” programs available to a
wide audience, with some assur-
ance that the programs are usable
as presented. I can testify that a
conscientious application of even
a few of the principles outlined in
this book will make you a better
programmer. It is my belief that
when a majority of practicing
programmers have read this
book, the software industry will
have taken a long step toward
maturity.

Jack W. Reeves

League City TX

Z-80 & 8080 Assembly
Language Programming
Kathe Spracklen
Hayden Book Co., Inc.

Rochelle Park NJ
Softbound, 165 pp., $7.95

Assembly-language program-
ming is an exciting pastime.
Therefore, I always keep my eye
out for new books on the subject.
I am especially interested in Z-80
programming since I recently
swapped my Sol for a Cromemco
Z-2. I sent for a copy of Sprack-
len’s book hoping to capitalize on
my 8080 experience and move
painlessly up to the Z-80.

I’ve accomplished my goal, but
not without learning a few things
that might be of interest to pro-
spective purchasers of this text.

The introduction to Z-80 &
8080 Assembly Language Pro-
gramming states that it is in-
tended for people who have some
experience in a high-level lan-
guage such as BASIC or FOR-
TRAN and want to tackle assem-
bly-language programming. It
also says it will provide just about
everything the applications pro-
grammer needs to know to get the
most out of his machine. Let’s see
how close to those designs the
book comes.

Starting with simple decimal-
binary-hex mathematics and then
moving into a discussion of bits
and bytes and CPU flags, the
author is beginning at the begin-
ning. To strengthen the learning
process, each chapter ends with a
series of exercises whose answers
can be found in the appendices.

Next come variables, and we’re
deeply involved in our subject, es-
pecially novices with no previous
assembly-language programming
experience. Unfortunately, at
this point, we’re only 14 pages in-
to the book. I started feeling early
that we were rushing things. Even
with my background I’d have

liked a little more explanation.

Much of the book discusses the
various 8080/Z-80 instructions
yet minimizes how to put them to
use or even why you’d want to use
them. Most of the “how” in-
volves exercises that present pro-
gramming problems and then use
commented source listings as the
answer. The information is all
there, but I feel that the beginner
will have trouble relating the text
and the listings to the actual pro-
gramming task.

In all examples where it is ap-
propriate, 8080, Zilog Z-80 and
TDL Z-80 mnemonics are given.
In many cases, 8080 program-
ming equivalents to the more
powerful Z-80 instructions are
listed.

The operation of all the in-
structions discussed is displayed
diagrammatically using symbols I
am sure are well known to profes-
sional programmers. These sym-
bols are not as well known to
computer hobbyists because they
do not appear on most keyboards.
Symbols such as < and >
would have been more familiar to
most of us if presented as <>,
<= and >=. Several others,
which I still don’t know the
meaning of, are used.

The final chapter concerns sav-
ing the programmer’s time and
saving processor time. Both are
laudable goals. Structured pro-
gramming is presented as the so-
lution to the first problem, and
reducing the number of processor
cycles required to complete a task
is advocated for the second. I
agree in both cases but would
have liked more discussion. As
with the rest of the book, I felt
that we were skimming along.

Am I being too critical? I tried
to take the author’s word that this
text was intended for the person
without any previous assembly-
language programming experi-
ence. However, I don’t think it is
possible to teach a subject as
complex as Z-80 programming
from scratch in 102 pages. Add 21
pages to list the 8080/Z-80 in-
struction sets and 43 pages of ex-
ercise answers, and you get 165
pages.

Z-80 & 8080 Assembly Lan-
guage Programming claims to be
ideal for self-study and for
schools. I agree that everything
necessary to program a Z-80
microprocessor in assembly
language is provided, and the
book was worthwhile. I just think
the material is covered too quick-
ly and without enough practical
application.

Rod Hallen
Tombstone AZ

Microcomputing January 1980 9

SMALL SYSTEMS JOURNAL

Introduction

In this month’s issue we will be concluding the multi-part series on Ohio Scientific’s
information management system, OS-DMS. Our objective in this issue is to give the
reader a brief description of the final three information management systems: Inven-
tory, Quotation/Estimation, and Testing/Tutoring which have not been shown in our
previous articles. Like the past articles, this issue also contains several reports which
were generated by these systems so that the reader might better understand the pur-
pose of the system.

OS-DMS QUOTA TION/ES TIMA TION SYSTEM

The OS-DMS Quotation/Estimation Package, like the other OS-DMS modules, utilizes
OS-DMS compatible master files and is specifically designed for a non-computer-
oriented user. The system is designed to aid the businessman whose activities involve
providing estimates or quotations as a part of his normal business proceedings. It pro-
vides a quick and easy method of making these calculations with the ability to generate
hard copies for further reference and customer presentation. The package also acts as
a prompter by displaying each factor that was previously defined, reminding the user to
consider each factor every time the program is run.

Because the user establishes each file and record, he can perform either general or
specific estimates. In the case of general estimates, the user would create a file con-
taining all of his inventory and other items, tangible or intangible, needing to be con-
sidered. Then, anytime a calculation would be needed, the user would be prompted by
each item that was previously entered. That is, each item would appear on the screen
before him for confirmation of use in that particular operation.

For specific estimates, the user would create a file containing only the items
necessary to perform that particular task. For example, a construction company would
create files for building, landscaping, or demolition estimates. Or, the files may be
broken down into even more specific functions such as building houses, building
garages or building barns. These files may contain such things as materials,
carpenter’s wages, bricklayer’s wages, operating expenses, transportation expenses,
fees for permits and overhead expenses.

Below is a copy of the Estimation System Menu.

OS-DMS ESTIMATION
Functions

(1) CREATE NEW ESTIMATION FILE

(2) EDIT ESTIMATION FILE

(3) PERFORM ESTIMATION

(4) ESTIMATION CHANGE AND/OR REPORT

(98) OS-DMS FILE DIRECTORY

(99) EXIT

OS-DMS ESTIMA TION SYSTEM OVER VIEW

The following is a short key to the programs on the menu.

CREATE NEW ESTIMATION FILE

This program allows the user to create new estimation files. The user specifies file
names, passwords, and the number of records per file. All other specifications, such
as the number of fields, the name of each field, and the maximum length of each
field, are predefined. The system then creates and initializes the estimation file
automatically.

EDIT ESTIMATION FILE

The Edit Estimation File program provides a means of modifying estimation files.
The user may specify a record number, an exact entry, or a search ‘string’ to access a
particular record.

PERFO RM ESTIMATION

The Perform Estimation program permits the user to run estimates based on the
items chosen for the estimate and the usage. Also, while performing an estimate,
the user may update the estimate file with relevant changes. In addition, the user has
the option of generating the estimate totals, an internal report, or a customer report.
ESTIMATION CHANGE AND/OR REPORT

This is a utility program which is capable of performing two basic functions. First,
it allows the user to modify or correct a previously defined estimate. Then, after cor-
recting the estimate, the user may run the corrected estimate without having to re-
enter the specifications.

OS-DMS FILE DIRECTORY

The OS-DMS File Directory selectively lists OS-65U files. The user specifies the
type of file(s) to display; the program scans through the OS-65U directory and prints
out the specified file names.

THE ESTIMA TION SYSTEM CAPABILITIES

Because of its ability to perform several special functions, the Quotation/Estimation
package can be cost justified by a businessman who performs frequent estimates for
projects or products. These functions include the generation of hard copy reports, built-
in edit features, reusable estimates, user specified options, and OS-DMS file com-
patibility. However, a businessman who performs only two or three estimates a year
would be better off performing the estimates manually and having his secretary type it.

The following is a brief discussion on each of the functions mentioned above.

1. The OS-DMS Estimation System has the ability to generate two types of hard copy
reports: an internal report and a customer report. Generating hard copies of the two
reports eliminates having to dictate the estimate form and figures to a secretary and
having her manually type the report.

2. There are three methods of editing the estimation files:

a. During the initialization of each estimate (while running “Per-
form Estimate”) any given item or the prices representing that
item may be modified. What this means is that instead of having to
manually edit the estimation file, the user can update each entry while run-
ning the estimate.

b . After running an estimate, if for some reason the user decides that the
estimate needs to be changed, updates can be made by running the
“ESTIMATION CHANGE AND/OR REPORT" program. This program lets
the user make the necessary changes and run the estimate again.

c . The third type of editor is the OS-DMS Editor which allows manual edit
functions at any time. The OS-DMS Editor is also the program that is used
for the initial entry of data in the files.

3. When running an estimate the user has two options that may be selected:

a . The user may add a variance to the totals for each heading. If a variance is
desired, the user also has the option of specifying the variance as an
amount or as a percentage of the totals per heading.

b . Secondly, the user must specify whether or not to display the profit margin
on the customer report and, if so, whether to calculate it on the retail or
the wholesale price.

4. The OS-DMS Estimation System is compatible with the other OS-DMS modules.
This common bond permits the user to link files, e.g., the estimation files to the inven-
tory files. This compatibility enhances the estimation module considerably because it
means that the OS-DMS Nucleus utilities can be used with the estimation programs.

THE ESTIMA TION S YSTEM REPOR TS

This system produces three types of reports shown below:

The Initial Entry Listing. This report indicates all of the inputs which were used to per-
form a given calculation.

‘..QUOTATION ESTIMATION— - (INITIAL ENTRY LISTING)

MASONRY MATERIALS
ITEM

WHOLESALE

RETAIL UNIT

CEMENT

6.15

8.00

PER 50 LB. BAG

5

SAND

230

5.00

A TON

2

GRAVE

1

8.00

15.00

A TON

1

ANCHOR BOLTS

.60

130

EACH

8

WIRE REINFORCING

.95

2.00

PER SQ. FT.

58

VARIANCE (Y OR N) Y

IS THE VARIANCE GOING TO BE

1) AN AMOUNT

2) A PERCENTAGE

1

AMOUNT Of VARIANCE
3

LUMBER

ITEM

WHOLESALE

RETAIL

UNIT

1x1

.01

.05

PER FT.

1x2

.03

.08

PER FT.

1 x4

.04

.12

PER FT.

100

1 x6

.05

.15

PER FT.

8

2x2

.05

.15

PER FT.

2x3

.06

.18

PR FT.

2x4

.08

20

PR FT.

342

2x6

.09

IS

PR FT.

66

2x8

.10

.30

PR FT.

2x10

.12

.35

PR FT.

2x12

.14

.40

PER FT.

4x4

.10

.30

PR FT.

4x6

VARIANCE

.14

(Y OR N) H

.40

PR FT.

PLYWOOD

ITEM

WHOLESALE

RETAIL UNIT

1/8 INCH

7.40

9.20 A SHEF 4x8

1/4 INCH

8.15

10.00 A SHEH 4x8

3/8 INCH

9.40

11.20 A SHEH 4x8

1/2 INCH

10.55

12.00 A SHEET 4x8

5/8 INCH

11.35

13.20 A SHEET 4x8

3

3/4 INCH

12.10

14.00 A SHEO 4x8

7/8 INCH

13.85

15.20 A SHEET 4x8

The second report is the Internal Report. The Internal Report is a company-oriented
report which contains the amount of usage for each item selected, the item, the
wholesale and retail prices, how the unit is sold, the totals per item, and the final totals
per heading. At the end of the report are the grand totals and the profit margin. The In-
ternal Report is primarily for managerial personnel so that they can analyze it and
decide whether or not the estimate is accurate and perhaps whether they should make
a bid on the project.

SACKER CONTRACTING INC.

22413 S. GROVE STREET
TOHKIi, NEW JERSEY 51227
785-6641

INTERNAL REPORT PAGE 1

DATE; 422/79 ESTIMATE VALID UNTIL 422/79

NAME BOB LINDEN
PROJECT: TOOL SHED

DESCRIPTION; 6 FT. WIDE, 8 FT. LONG 4 7 FT. HIGH (BUILD OUT Of WOOD)

MISC

ESTIMATED TIME Of COMPLETION: 2-3 DAYS

MASONRY MATERIALS

USAGE

ITEM

WHOLESALE

RETAIL UNIT

WHSl TOTAL

RETAIL TOTAL

5

CEMENT

6.15

8.00 PER 50 LB. BAG

30.75

40.00

2

SAND

230

5.00 A TON

5.00

10.00

1

GRAVE

8.00

15.00 A TON

8.00

15.00

8

ANCHOR BOLTS

.60

130 EACH

4.80

12.00

58

WIRE REINFORCING

.95

2.00 PER Sa FT.

55.10

116.00

VARIANCE

3.00

3.00

3.00

3.00

TOTAL

106.65

196.00

LUMBER

USAGE

ITEM

WHOLESALE

RETAIL UNIT

WHSl TOTAL

RETAIL TOTAL

100

1 x4

.04

.12 PER FT.

4.00

12.00

8

1 x 6

.05

.15 PER FT.

.40

1.20

342

2x4

.08

.20 PB FT.

27.36

68.40

66

2x6

.09

.25 PR FT.

5.94

16.50

T0TAI

3770

98.10

PLYWOOD

USAGE

ITEM

WHOLESALE

RETAIL UNIT

WHSL TOTAL

RETAIL TOTAL

8

3/8 INCH

9.40

1170 A SHEH 4x8

7570

89.60

3

58 INCH

11.35

1370 A SHEET 4x8

34.05

39.60

TOTAL

109.25

129.20

LABOR

USAGE

ITEM

WHOLESALE

RETAIL UNIT

WHSl TOTAL

RETAIL TOTAL

12

CARPENTER

10.40

20.00 AN HOUR

124.80

240.00

4

MANUAL LABORER

8.60

15.00 AN HOUR

34.40

60.00

TOTAL

159.20

300.00

MISC. MATERIALS

USAGE

ITEM

WHOLESALE

RETAIL UNIT

WHSl TOTAL

RETAR. TOTAL

1

TAR PAPER

6.65

8.40 A ROLL

6.65

8.40

3

SHINGLES

18.10

2170 A BUNDLE

54.30

63.60

2

NAILS

375

430 A LB.

6.50

9.00

TOTAL

67.45

81.00

..RETAIL PRICE IS $804.30*.
.WHOLESALE PRICE IS $480.25*.
..PROHI MARGIN IS $324.05*.

Finally, the Customer Report is similar to the Internal Report, except that it does not
display any of the wholesale numbers and the user must specify whether or not to
display the profit margin on the report. If the profit margin is on the report, the user must
also specify whether the profit margin should be calculated on the wholesale or retail
cost and, unlike the Internal Report, the profit margin is displayed as a percentage.

SACKER CONTRACTING INC.

22413 S. GROVE STREET
TONKLE, NEW JERSEY 51227
785-6641

CUSTOMER REPORT PAGE 1

DATE: 4/22/79 ESTIMATE VALID UNTIL: 672/79

NAME: BOB LINDEN
PROJECT: TOOL SHED

DESCRIPTION: 6 FT. WIDE. 8 FT. LONG & 7 FT. HIGH (BUILD OUT Of WOOD)
MISC.

ESTIMATED TIME OF COMPLETION: 2-3 DAYS

MASONRY MATERIALS

USAGE

ITEM

COST UNIT

TOTAL

5

CEMENT

8.00 PER 50 LB. BAG

40.00

2

SAND

5.00 A TON

10.00

1

GRAVEL

15.00 A TON

15.00

8

ANCHOR BOLTS

1.50 EACH

12.00

58

WIRE REINFORCING
VARIANCE

2.00 PER SO. FT.

3.00

116.00

3.00

FINAL TOTAL

196.00

LUMBER

USAGE

ITEM

COST UNIT

TOTAL

100

1x4

.12 PER FT.

12.00

8

1x6

.15 PER FT.

170

342

2x4

.20 PER FT.

68.40

66

2x6

.25 PER FT.

16.50

FINAL TOTAL

98.10

PLYW00O

USAGE

ITEM

COST UNIT

TOTAL

8

18 INCH

11.20 ASHST4X8

89.60

3

38 INCH

1370 A SHffT 4x8

39.60

FINAL TOTAL

129.20

LABOR

USAGE

ITEM

COST UNIT

TOTAL

12

CARPENTER

20.00 AN HOUR

240.00

4

MANUAL LABORER

15.00 AN HOUR

60.00

FINAL TOTAL

300.00

MISC. MATERIALS

USAGE

ITEM

COST UNIT

TOTAL

1

TAR PAPER

8.40 A ROLL

8.40

3

SHINGLES

21.20 A BUNDLE

63.60

2

NAILS

4.50 A LB.

9.00

FINAL TOTAL 81.00

.ESTIMATED PRICE IS $804.30**
..PROFIT MARGIN IS 4078%..

OS-DMS TESTING /TUTORING SYSTEM

Today, the educational challenge is great! That is why instructors are constantly
searching for learning aids and better methods of teaching. Instructors have found that
if some types of audio-visual aids are used, students tend to learn more quickly and
easily. Examples of such aids are slides, films, field trips and, the newest and latest
audio-visual aid, the computer.

With our ever-growing technology, scientists are constantly discovering new tasks
the computer can perform. The computer promises to turn the day to day operations in-
to a lifetime learning process.

To aid the teacher in the classroom, Ohio Scientific has developed the OS-DMS Educa-
tional System. It is designed to allow a teacher who is not trained in the use of a com-
puter to quickly and efficiently set up a quiz or tutorial session, have the students do the
required work on the computer, and then give the student a grade and record the grade
automatically. Additionally, it allows the teacher to define practically any type of test or
lesson desired, depending on the program specifications defined.

OHIO SCIENTIFIC 1333 S. Chillicothe Road • Aurora, Ohio 44202 • (216)562-3101

The OS-DMS Educational System is obviously not a business package, but it could
possibly be tied in with our business applications. For example, a school could pur-
chase the Educational System to be used by all the instructors as an aid in tutoring and
giving quizzes. If the Educational System seemed to be a success with the students
and the instructors, the school could then purchase the Account Payable/Receivable,
Personnel, General Ledger, and possibly the Inventory system. By setting up model ac-
counts and companies on these systems, the students in the business courses such as
general business, bookkeeping, accounting, etc., can get first-hand experience in real
life situations. Because the OS-DMS modules are systems that are written for real life
applications, the school could additionally use these systems for their own purposes.

The following is a copy of the Instructor’s Menu:

OS-DMS EDUCATIONAL SYSTEM
Function s

(1) CREATE A GRADE FILE

(2) CREATE A QUIZ OR TUTOR FILE

(3) REVISE A QUIZ OR TUTOR FI LE

(4) REVIEW A GRADE FILE

(5) SCORE CONFIRMATION

(6) DMS FILE DIRECTORY

(98) RETURN TO THE STUDENT MENU

(99) EXIT

OS-DMS EDUCA TIONAL OVER VIEW

The following is a short key to the programs on the Instructor’s Menu.

CREATE A GRADE FILE

This allows the instructor to create Grade Files. The Grade File contains the name of
each student, student number, the total number of possible points for each quiz, the
number correct and the number incorrect. The instructor specifies the device the file is
to be stored on, the file name, the password, and the number of students to be included
in the file.

CREATE A QUIZ OR TUTOR FILE

Before a quiz or tutor can be written, the instructor must create Quiz or Tutor files.
The Quiz and Tutor files are similar except that the first letter of a quiz must begin with a
“Q” and the first letter of a tutor must begin with a “T’\ Both contain the questions, the
answer to each question, two miscellaneous fields and the points that each question is
worth. The instructor specifies the device the file is to be stored on, the file name, the
password, whether this is a Quiz or Tutor file, the number of questions, and the max-
imum number of lines to reserve for each question.

REVISE A QUIZ OR TUTOR FILE

This program provides a means of editing Quiz and Tutor files. It also has other built-
in features such as the ability to generate a hard copy of a quiz or tutor, allowing the in-
structor to erase an entire Quiz or Tutor file and permitting him or her to set certain
specifications for a Quiz or Tutor file.

REVIEW GRADE FILE

This program provides editing features, permits easy retrieval of student scores, has
the ability to append and delete students, and can generate a printed listing of all the
students and their scores.

SCORE CONFIRMATION

After the deadline for taking a quiz has passed, the instructor is required to run this
program. This program looks in the Grade File to see what students have not taken the
quiz. Whenever a student does not have a score recorded for the latest quiz, the pro-
gram gives that student a zero for the quiz score, and displays a list of the students who
did not take the quiz.

THE EDUCA TIONAL SYSTEM CAPABILITIES

The OS-DMS Educational System was designed to assist instructors in two primary
areas of teaching: tutoring and testing. Both have several special built-in features
which make the Educational System quite unique. Since all instructors do not give
tutors and quizzes in the same fashion, these features are essential because they allow
the teachers to individualize their lessons and quizzes.

The following is a brief discussion on each of the features for a tutor and a quiz.
TUTOR

Tutors can be used for a wide variety of applications. Some instructors might use the
tutoring program to assist those students that are having difficulty in their classes,
others might use it to test one's knowledge and others as a review for finals.

The operational decisions to be made by the instructor when setting up a tutorial ses-
sion are as follows:

1. Specify whether or not Structured Learning should be used.

Structured Learning is a tutoring program specifically designed to use multiple
choice and/or matching questions. Structured Learning reviews any particular topic:

i.e., the capital of each state or the presidents of the United States. The program begins
by displaying the first question with four possible choices. If an incorrect answer is
chosen, the program will tell the student why the answer he chose was wrong and will
ask the same question again. This process will continue until the question is answered
correctly.

Note:

A Tutor file established for Structured Learning must pertain to one particular topic
throughout the file; the program randomly selects three answers from any question in
the file. If the file does not pertain to a particular topic, the three answers selected may
not relate with the question.

2. Select the Input/Output (I/O) device.

If a line printer is available, the instructor has the option of generating a hard copy of
the questions, the student’s answers and the student’s score. The purpose for
generating a hard copy of the tutor is to supply the student with a study sheet as a
review for finals or to give the instructor written results of how much his students have
remembered from a past quiz or lesson.

3. Specify whether or not the student should have a second chance to answer each
question correctly.

4. Specify whether or not the student should be told the correct answer after the
question has been answered incorrectly.

5. Specify whether the student should be shown the score.

6. If a Level III machine is available, the instructor may specify a time limit for the
tutor.

QUIZ

Like tutors, quizzes also can be written and used in a variety of ways. Because of this,
the quiz program also has several built-in features. Unlike the tutor, however, when a
quiz is being run, the program automatically checks if the student taking the quiz has
taken it before. It also checks to see if the student number exists. If the student has
taken the same quiz before or the student number does not exist, the program will in-
form the student that he cannot take the quiz and will exit the system. Also, after a quiz
has been taken, the program automatically writes the student’s score in the student
grade file.

The operational decisions to be made by the instructor when setting up a test are as
follows:

1. Select the Input/Output (I/O) device.

Since the student’s answers to individual questions are not recorded anywhere, the
instructor might want to generate a hard copy of each student’s quiz. Later, after the
quiz, the instructor could distribute the quiz papers and go over the questions with the
students.

2. Specify whether to display the questions randomly or sequentially.

This feature helps eliminate possible cheating by students. If the questions are
scrambled for each student, the passing of answers would be useless unless the stu-
dent wrote down each question and the answer to it.

3. Specify whether the student should be shown his score.

4. If a Level III machine is available, the instructor may specify a time limit for the
quiz.

THE OS-DMS INVENTOR Y CONTROL SYSTEM

The OS-DMS Inventory Control System is an automated computer system designed
to provide the end user with specific information concerning the current status of the
inventory. This system is menu oriented so only minimal computer knowledge is need-
ed.

There are three sub systems which make up the Inventory Control System: the Inven-
tory System, the Purchasing System, and the Bills of Material System. These sub-
systems were designed to run independently or in an integrated mode. If a particular
end user is using all three systems, data may be passes from one to the other. This
allows the end user to slowly integrate computerized operations into the business
without sacrificing the benefits of integrated business software.

INVENTORY SYSTEM

The Inventory System enables the inventory control clerk to accurately keep track of
the current inventory levels and value. This is accomplished by providing the functions
shown on the following menu:

OS-DMS INVENTORY MENU

(1) CURRENT QUANTITY IN STOCK REPORT

(2) INVENTORY USAGE STATUS REPORT

(3) REORDER REPORT

(4) CURRENT INVENTORY VALUE REPORT

(5) ARCHIVE INVENTORY REPORT

(6) GENERAL CONDITIONAL INVENTORY REPORT

(7) ORDER ENTRY
(S) STOCK CHECK

(9) RELIEVE OR SHIP ITEMS FROM INVENTORY

(10) RECEIVE ITEMS INTO INVENTORY

(11) UPDATE CURRENT QUANTITY IN STOCK VALUES

(12) GENERAL INVENTORY EDIT

(13) SET A REORDER LEVEL

(14) SET AN AVERAGE USAGE

(15) ALPHABETIZE INVENTORY RECORDS

(16) COPY OR BACKUP DISKETTES
(99) EXIT

t

These functions can be divided into three areas: the report writers, the day to day
operations, and the maintenance functions.

The report writers are used to inform management of the status of the inventory. The
Inventory Usage Status Report provides detailed information such as average weekly
usage, weeks on hand and weeks on order for each inventory item. The Inventory Value
Report calculates the current value of the inventory using the average unit costs. A
general report writer is included to handle the occasional reports that are requested.

The day to day operations such as stock checks, entry of received goods and inven-
tory adjustments have been optimized for maximum speed and accuracy. A record is
made of all input transactions to aid in the correction of input errors. The order entry
program will mark items ordered and generate an invoice.

The maintenance functions allow the end user to make copies of the inventory data
in case an error occurs, and to keep the inventory master file in alphabetical sequence.
Again, the programs prompt the user with simple, easy to understand instructions.

Throughout the OS-DMS business systems, the amount of computer knowledge the
operator needs has been kept to a minimum. This means that any person capable of
performing the same business task manually will be able to use this software with
minimal instruction.

There are several features that help make this Inventory System useful to the small
businessman.

The system maintains an average weekly usage for all items in the inventory. When a
stock check is performed, the computer provides a detailed description of the item’s
current status. The average weekly usage is used along with the quantity in stock and
quantity on order values to obtain weeks on hand and weeks on order figures. The cur-
rent average unit cost is used to determine the value of the inventory. With this data, the
inventory clerk has a more informative picture of the state of inventory than a simple
quantity in stock report or a reorder report.

When a part breakdown is finished, the end user can direct the computer to either in-
crement or decrement an inventory file with the results of the breakdown or print the
results in alphabetical order on the terminal or printer. This system provides a means of
tracking inventory items that cannot be easily counted manually. The weekly shipping
list can be broken down or exploded into raw inventory components. These figures
could be used to adjust the quantity in stock figures for those items.

The Bills of Material System can be integrated into the Inventory Control System.
When a bill of material is being printed, the end user has the option of having the com-
puter look at the inventory file for the description and the latest average unit cost for
each component on the bill. This means that the bill of material will have the latest and
most accurate description and price. This eliminates the need for the double entry of
data when the cost or description changes.

PURCHASING SYSTEM

EXPLOSION FILE DUMP

PAGE: 1

The Purchasing System keeps track of the open purchase orders for inventory items.
The purchasing clerk can quickly determine if a particular part is on order and, if so,
with which vendors. The Overdue Order Age Analysis will list the purchase orders that
are overdue. The Outstanding Order Age Analysis will list all currently outstanding pur-
chase orders.

If a particular end user has the Inventory System and the Purchasing System, they
may be integrated. Each system will remain independent in that minor changes to the
operation of the Purchasing System will not interfere with the Inventory System. The
Purchasing System is capable of posting the quantity on order for each item into the In-
ventory System. With these figures, the Inventory System can generate an inventory
value report with the dollar value on order for each part. When a part is received by the
receiving clerk and entered into the Inventory System, the Inventory System increments
the quantity in stock field and decrements the quantity on order figures.

INVENTORY SYSTEM

OS-DMS PURCHASES MENU

(1) PURCHASES MASTER UPDATE

(2) PRINTD1SPLAY PURCHASES JOURNAL

(3) COMPLETE PURCHASES MASTER DUMP

(4) CONDITIONAL PURCHASES MASTER DUMP

(5) PURCHASES MASTER EDIT

(6) PRINT AGE ANALYSIS-OVERDUE ORDERS

(7) PRINT AGE ANALYSIS-ALL OUTSTANDING ORDERS

(8) CREATE NEW PURCHASES MASTER FIE

(9) PRINT PART NUMBER LIST

(10) BACKUP PURCHASES MASTER FIE

(11) EXIT PURCHASES SYSTEM

?

BILL OF MATERIAL AND EXPLOSION FUNCTIONS

(1) INTRODUCTION.

(2) EXPLOSION INPUT FUNCTIONS.

(3) EXPLODE ITEMS ALREADY ENTERED.

(4) EXPLOSION OUTPUT FUNCTIONS.

(5) LIST ALL SUBASSEMBLIES THAT CAN BE EXPLODED.

(6) LIST A BILL OF MATERIAL FOR A SUBASSEMBLY.

(7) CREATE A BILL OF MATERIAL FILL

(8) EDIT A BIL OF MATERIAL FILE.

(9) DELETE A BILL Of MATERIAL FILE.

(10) CREATE A COPY OR BACK UP A DISKETTE.

BILLS OF MATERIAL SYSTEM

The Bills of Material System allows for the creation, modification and deletion of bills
of material for inventory subassemblies as well as the automatic breakdown of sub-
assemblies into their component parts. The functions are selected through a menu
system.

Before a part breakdown or explosion can be run, the end user must enter a bill of
material for every item that can be broken down. Once these bills have been entered,
the end user can have the computer break down finished goods and subassemblies in-
to their component parts. The maximum number of levels of breakdown or explosion for
a particular item depends on the number of levels in the bills of material for that item.
For example, a particular business manufacturer’s television set has twenty sub-
assemblies itemized on its bill of material. If each of the twenty sub-assemblies has a
bill of material, the system can do a two-level breakdown. It is common to have another
bill of material for most or all of the items on each of the sub-assemblies’ bills of
material. This would permit the system to perform a three-level breakdown or explo-
sion. This can be expanded to whatever depth the end user desires. The following is a
multi-level breakdown

PART NUMBER: CA-6CP

DESCRIPTION: GENERAL PURPOSE I/0-MEM0RY BOARD

PART NUMBER

QUANTITY DESCRIPTION

TOTAL COST

PC-61

1

ACCESSORY BOARD

16.42

SC-12MM

2

12 PIN MA M0LEX PLUG 09-64-1121

.27

SC-16FI

10

16 PIN INTEGRATED CIRCUIT SOCKET

1.20

SC-18FI

48

18 PIN INTEGRATED CIRCUIT SOCKET

6.96

SC-24FI

1

24 PIN INTEGRATED CIRCUIT SOCKET

.18

SC-40FI

3

40 PIN INTEGRATED CIRCUIT SOCKET

.89

C-151

2

150 PF.

.10

C 102

2

.001 MF.

.14

C-506

2

50 ML

.16

CB-10410

39

.1 MF. BYPASS 10 VOLT

1.70

R1-102

4

IK OHMS 1/4 WATT 5%

.04

R1-221

12

220 OHMS 1/4 WATT 5*

.12

R1-391

12

390 OHMS 1/4 WATT 5%

.12

R1-471

8

470 OHMS 1/4 WATT 5%

.08

R1-472

2

4.7K OHMS 1/4 WATT 5%

.02

RP 103

4

10K OHMS TRIMMER POT.

1.64

IC74LS00

1

m

.21

IC74LS04

2

TTl

.33

IC74LS02

1

TU

.16

IC-74LS10

1

TTl

.14

IC-7417

4

TTl

.76

IC-74LS20

1

TTl

23

IC-74LS93

1

TTl

26

IC-74123

2

m

.64

1C 7415138

4

TTl

1.40

IC-74LS390

3

TTl

2.13

IC-8T28

2

BUFFER

1.62

IC-8T95

3

BUFFER

1.89

IC-68B50

1

PIA

4.00

IC-68B21

1

PIA

4.00

10121 14-550

32

RAM

116.80

HW-SP.75

4

PUS. SPAC. 3/4 L SMITH 4167

.12

HW-WAN

8

NYLON WASHER HH SMITH 2673

.09

HW-56321.25

4

SCREW 1-1/4 x 6-32

.04

W-406J

1

40 C0ND 6" L FI CA JUMP AP PROD

4.52

W-1ST18

1,FT-

1 CONDUCTOR STRANDED 18 GA.

.03

SC-3FC

1

3 PIN FE M01EX CON 03-09 1032

.05

SC-1FTM

2

FEM. TERKM0L. 02-09-1118

.02

SC-1MTM

2

MALE TERM. MOL. 02 092118

.02

SUMMATION OF TOTAL COSTS USING CURRENT INVENTORY AVERAGE UNIT COSTS = 169 JO

SUMMARY

The OS-DMS Inventory Control System is comprised of three independent sub-
systems: the Inventory System, the Purchasing System, and the Bills of Material
System. These systems may be run in an independent or integrated mode depending on
the degree of sophistication the end user desires. The overall system is flexible enough
that it can be implemented in stages to allow the end user time to adjust to computer-
ized business methods. These three systems, when combined with the other OS-DMS
business packages, represent a major step in the development of efficient, easy to use
microprocessor-based business software.

OHIO SCIENTIFIC 1333 S. Chillicothe Road • Aurora, Ohio 44202 • (216)562-3101

PET-POlim

Robert W. Baker

This is my first issue as author
of the PET-pourri column; I
hope to continue providing inter-
esting and useful information on
the PET. With only a week to as-
semble this first installment, I
didn’t have enough time to gather
much information on new prod-
ucts. By the next issue, I hope to
find more products to review, or
at least be able to provide more
information.

I’ve been requested to review
more programs and hardware ac-
cessories for the PET whenever 1
can acquire them for evaluation.
Since most PET owners still buy
via mail order. I’ll try to provide
as much information as possible
on each product I learn of or try
on my own system. This should
make it easier to choose the items
of greatest interest for your par-
ticular system. It has been sug-
gested, however, that I avoid re-
viewing game programs unless
they are extraordinary.

I’ll also try to include program-
ming tips and ideas that I feel
may be of value. If you’d like to
share any of your own program-
ming tricks or newfound secrets
of the PET operating systems. I’d
be happy to hear from you. I have
one request: Please enclose an
SASE if you expect a reply. All
mail should be addressed directly
to me and not through the maga-
zine to avoid forwarding delays.

New Products
and Publications

A new printer manufactured
by Shinshu Seiki is available for
the PET, and it appears similar to
the Commodore printer. The
Model TX-80 dot-matrix impact
printer operates at 150 characters
per second. It is available with
friction feed or tractor feed and
uses standard paper, four to ten
inches in width. With 80 charac-
ters per line, double-size charac-
ters and PET graphics, it ap-
peared to be a nice unit when dis-
played at PCC ’79 in Philadel-
phia last fall. The printer has
been advertised under several
names and at varying prices, but
lists for about $900 with tractor
feed and all interface cables for
the PET.

If you have an 8K PET and still
haven’t replaced your small key-

board, I suggest you check the ar-
ticle in the October 1979 issue
(page 82) on the keyboard from
Century Research & Marketing.
Having used one for several
months, I’ve discovered I like the
keyboard with the molded-in
graphics and expanded numeric
pad.

The PET Gazette has become a
full-size, bimonthly magazine
called Compute, the Journal for
Progressive Computing. The
magazine is divided into four sec-
tions:

• 6502 section with articles of in-
terest to everyone with a 6502-
based machine.

• Business and industrial appli-
cations.

• Educational guide to teachers.

• Gazettes for each “special”
machine, including the PET, Ap-
ple, Atari and single-board com-
puters (SBCs).

Mail-order subscriptions are $9
per year, and the magazine is
published by Small Systems Ser-
vices, Inc., 900 Spring Garden
St., Greensboro NC 27403. The
sample issue distribued at PCC
’79 was impressive; hope they
keep up the good work.

Both Instant Software, Peter-
borough NH, and New England
Electronics (NEECO), 679 High-
land Avenue, Needham MA
02194, have been distributing
new catalogs. If you haven’t re-
ceived one yet, I suggest you write
for one soon. NEECO’s General
Ledger program is available; I
hope to have details on it in time
for the next issue.

What About
the Axiom Printers?

Although the Axiom electro-
static printers for the PET have
been available for over a year,
there has been very little mention
of these printers in most PET
publications or columns. Two
models of interest to PET owners
offer uppercase and lowercase al-
phanumerics as well as all PET
graphics. The EX-801 PET mod-
el is a general-purpose printer,
while the EX-820 PET model
provides true reproduction of the
PET graphics by eliminating ex-
tra spacing between printed lines,
as occurs on the EX-801. The
small, quiet printers have a print

speed of 120 lines per minute.
They were designed to require a
minimum of maintenance, and
the printhead should last for one
to two million lines of printing.
This is roughly equivalent to
about 140 rolls of paper; a re-
placement printhead is available
for $45.

The printers provide functions
that are selected using various
control characters as follows:
LIST MODE, CHR$(9) —

All cursor controls are printed
as shown on a normal screen list-
ing. This is the mode selected au-
tomatically at power-on or on-
line and is used for printing BA-
SIC program listings.

PRINT MODE, CHR$(8) —

All output is printed as it would
be displayed on the screen during
program execution. Cursor right
and SPC commands produce
printed spaces, while other cursor
controls are ignored. TABs and
number formatting using the
comma may not produce correct
results.

40 COLUMN, CHR$(12) —

Selects 40-column printout,
which is normally selected auto-

matically at power-on.

80 COLUMN, CHR$(11) —
Selects 80-column printout un-
til 40-column printout is re-se-
lected. Character sizes may be in-
termixed in any combination on a
line however desired by switching
back and forth between the two
sizes.

GRAPHICS, CHR$(15) —
Prints PET graphics and up-
percase letters providing printout
compatible with the POKE
59468,12 mode on the PET.
LOWERCASE, CHR$(14) —
Prints lowercase alphabetic in
place of graphics the same as a
POKE 59468,14 on the PET.
Character types may be inter-
mixed on a line by switching
modes back and forth if graphics
are desired along with uppercase
and lowercase letters.

BELL, CHR$(7) —

Sounds the internal buzzer for
1/4 second when the line is
printed containing this control
mode.

Two other control characters
are listed in the manual to turn
the loudspeaker on and off for di-
rect program control of sound ef-

10 REM TAPE HEX DUMP PROGRAM
20 REM BY: ROBERT W. BAKER
30 REM

40 REM DISPLAYS A HEX DUMP OF
50 REM TAPE DATA FILES.

60 :

70 H$="0123456789ABCDEF"

80 PRINT"L*TAPE HEX DUMP"

90 PR I NT : PR I NT : PR I NT " H I T ANY KEY TO"
100 PR I NT "HOLD/CONTINUE THE DISPLAY."
110 PRINT: PR I NT "HIT 'D' WHEN DONE TO"
120 PRINT"STOP BEFORE END OF FILE."
130 PRINT: PRINT
140 OPEN 1
150 S$="

160 PRINT"tTAPE HEX DUMP" : PRINT: PRINT
170 B=0: GOTO 250
180 GET#1,C$

190 IF ST <> 0 THEN 320
200 A=ASC<C$>:A1 = INT<A/16>

210 PRINT MID$(H$,fll+l,l);

220 PRINT MID$<H$,A-<A1*16>+1,1
230 B=B+1

240 IF INKB/10) <> B/10 THEN 278
250 PRINT

260 PRINT RIGHTS S$+STR$<B), 5 >":

270 GET C$: IF C$="" THEN 180
280 IF C$="D" THEN 320
290 GET C$:IF C$="" THEN 290
300 IF C$="D” THEN PRINT: END
310 GOTO 180

320 PRINT: PRINT: PR I NT “ST =";ST

Listing 1. Tape hex dump program.

14 Microcomputing January 1980

fects.

I've not been able to make this
work, and no information is pro-
vided on how to use the controls.
The printers do provide automat-
ic printing on the reception of the
81st, 41st or equivalent character,
depending on the line characteris-
tics.

The IEEE interface board
mounts on the back of the PET at
the IEEE bus connector with a
ribbon cable connected to the
printer. The interface board pro-
vides a true IEEE bus connector
in addition to reproducing the
IEEE edge connector of the PET
for other Commodore products.
The printer is connected via the
IEEE interface but will recognize
any device address on the IEEE
bus. This was probably done to
eliminate the costly circuitry to
recognize a specific device ad-
dress on the IEEE bus and keep
the printer cost at a minimum.
However, a switch on the front
panel of the printer does allow the
user to put the printer on or off
line to avoid this problem of
recognizing all bus addresses.

Two other switches on the
printer provide manual paper
feed and a built-in self-test mode.
When the printer runs out of pa-
per, the bell will sound continu-
ously and all printing will stop.

Having used an EX-801 for
over six months now on my own
system, I’ve been impressed by
the print quality and the printer
reliability. Having the capability
of producing true listings of BA-
SIC programs with all cursor con-
trols shown has saved many
hours of work on several occa-
sions. My only dislike is the 5 1/2
inch wide electrostatic paper that
costs about $6 per roll and can be
hard to find on occasion . . .
probably the major drawback of
this type of printer. However, a
300-foot roll of paper usually
lasts for well over a month on my
system, even with very heavy use.

If the impact printers are too
expensive for your current bud-
get, but you definitely need a
printer, you should consider the
$495 EX-801 Axiom printer, with
the ability to get true program

listings compared to other low-
cost printers that do not print all
PET graphics. If you do decide to
get an Axiom printer, make sure
you get a model designed for the
PET with the IEEE interface.
Axiom markets a complete line of
printers, and the PET models
have a special internal ROM in
addition to the IEEE interface to
provide all the particular features
for the PET.

Programming
Ideas and Tips

If you are experimenting with
tape data files, this simple pro-
gram (Listing 1) can help display
the exact contents of any data
file. It reads the file byte-by-byte
and displays the hexadecimal
value of each byte in the file, in-
cluding all separator and control
characters. The display will list
ten bytes per line with a byte
count indicated in the left col-
umn, which makes it extremely
easy to determine the exact for-
mat of any data file.

Machine-language programmers
might be interested in the follow-
ing two routines that are con-
tained in the older 8K PET oper-
ating system. I plan to check
where these routines are located
in the new operating system in the
near future. I should be getting
my new ROM set any day.

Block Move: This routine will
move the contents of a contigu-
ous block of memory locations
from one area of memory to a
new area of memory. The routine
starts at hex location $C2E1
(49889 decimal) and uses the fol-
lowing pointers in low memory,
which must be set prior to calling
this subroutine.

Joystick Control #1

Connector pin

2

3

4

5

6
7
S
9

Wire color Joystick function (switch)

***no connection***

Brown Right

Green Left

Blue Bottom

White Top

***no connection***

Black (switch common)

***no connection***

Orange Button

Joystick Control #2

$A9 = hex $E8 (232 decimal)
$AA = hex $83 (131 decimal)

$ AE = hex $00

$AF = hex $80(128 decimal)

$ A7 = hex $00

$A8 = hex $20 (32 decimal)

. top address = hex $83E8

(33768 decimal)

. bottom address = hex $8000

(32768 decimal)

. new top address = hex $2000

(8192 decimal)

1000 byte
display RAM
to be saved . . .

.... $83 E8 (33768 decimal)

= top of area to be saved + 1

$8000 (32768 decimal)

= bottom of area to be saved

$2000 (8192 decimal)

= top of new area + 1

.... bottom of new area, new area same
length as the old area

Example 1.

Hex locations $A9 and $AA
(169 and 170 decimal) contain the
address, plus one, of the last byte
to be moved, the upper limit of
the old area. Hex locations $AE
and $AF (174 and 175 decimal)
contain the address of the first
byte to be moved, the lower limit
of the old area. Hex locations
$A7 and SA8 (167 and 168 deci-
mal) contain the address, plus
one, of the last byte to be moved
to, the upper limit of the new
area. All address pointers are in
the standard format of the low
byte of the address first then the
high byte of the address.

As an example, suppose you
wanted to move the 1000 bytes of
the display RAM into the top of
your 8K program RAM to save
the data for some reason. Before

calling the block move subroutine
you would set the pointers as
shown in Example 1.

Search for a BASIC Line Number:
This routine will search through
all the lines of a BASIC program
in memory looking for a specific
line number. The line number to
be found must be placed in loca-
tions 8 and 9 prior to calling this
subroutine at hex location $C522
(50466 decimal). The line number
is stored in standard address for-
mat, low byte first. On return
from the subroutine, the proces-
sor carry bit will indicate whether
the line number was found or not.
The carry bit will be clear (0) if
the line was not found. If the line
was found the carry bit will be set
(1) and hex locations $AE and
$AF (174 and 175 decimal) will

Orange (9)

Brown (2).
Green (3).
Blue (4).
White (5).

(button)

Black (7),

Black (7).

Brown (2).
Green (3).
Blue (4),
White (5).

Orange (9)

(button)

User Port
Connector Pin

User

Port

Connection

,C (right)

D (left)

,E (bottom)
.F (top)

1, 11, 12, A or N

H (right)

,J (left)

,K (bottom)
,L (top)

PA0

PA1

PA2

PA3

System ground

PA4

PA5

PA6

PA7

Joystick connector wiring and interface to PET user port.

Microcomputing January 1980 15

COMPUTER CLINIC

contain the address of where the
line is located in memory.

This routine can then be used
to create self-modifying pro-
grams, store data within a pro-
gram DATA line or delete pro-
gram instructions. I hope to cover
some of these fancy program
tricks in future columns. They’re
quite easy once you’ve tried them.

Simple Joystick Interface
for the PET

Cursor magazine is providing
some of the best software for the
PET, with some very fancy games
currently available. Now that
they are providing more pro-
grams that use joysticks, you may
want to add a pair to your system
to take full advantage of these
new programs. Cursor's pro-
grams are designed to work with
all three of the dual Atari joystick
adapters currently available from
Coyote Electronics, Box 101,
Coyote CA 95013; Creative Soft-
ware, Box 4030, Mountain View
CA 94040; Chuck Johnson, 17104
Via Alamitos, San Lorenzo CA
94580.

If you’d rather construct your
own interface, the joysticks can
be ordered directly from Atari.
Sears Roebuck and Co. lists them
on page 651 of their Christmas
Catalog at $9.95 each (catalog
#6C99835). The accompanying
diagram shows a simple interface
to connect two joysticks to the
PET user port. The joysticks
come with a 9-pin subminiature-D
connector at the end of the con-
necting cable. Mating connectors
are rather expensive and may be
hard to find. You may want to
cut these connectors off and wire
the joysticks directly to your user
port connector. The diagram
shows both the connector pin
number and the internal wire col-
or for whichever scheme you
choose to use.

The interface simply connects
each switch to a separate input
line of the user port. The joystick
button is then connected to the
TOP and BOTTOM switches, us-
ing two diodes to isolate the three
switches. This combination pro-
vides a unique 4-bit code at the
user port for each joystick posi-
tion. I haven’t been able to com-
pare this interface with those
commercially available, but it
does work well with the Cursor
programs.

Please address any correspon-
dence to: Robert W. Baker, 15
Windsor Drive, Atco NJ 08004.

The Craig County Virginia
Public Schools have recently
placed Level II TRS-80s in pilot
programs in both elementary and
secondary schools. These ma-
chines are being used with com-
puter-assisted instruction (CAI)
and educational programs. Be-
cause of an apparent scarcity of
CAI programs, K-12, school per-
sonnel and advanced secondary
students are developing such pro-
grams. This process is slow, how-
ever, when the ultimate objective
is to offer CAI in a variety of sub-
jects at all grade levels. We would
be glad to contact schools and/or
individuals interested in exchang-
ing programs they have devel-
oped.

Earl R. Savage
Craig County Public Schools
PO Box 245
New Castle VA 24127

I have a terminal of unknown
origin (CRT, power supply,
boards and keyboard). The only
identification I can find is a label:
BA Sanders Associates, Inc.,
Data Systems Division, Model
722-1 FI, Serial #ED0170, NFPA
Type II. Does anyone out there

Washington DC

The Washington Amateur
Computer Society is an organiza-
tion dedicated to personal com-
puting. WACS meets at 7:30 pm
on the last Friday of each month
in the first-floor lecture hall of
Keane Hall, Catholic University
of America. Contact WACS c/o
4201 Massachusetts Ave. #168,
Washington DC 20016.

Danvers MA

HUG Northshore, a computer
club for Heathkit computer
users, meets the second Wednes-
day of each month (7 pm) at Hill
Tech Building, 88 Holten St.
(third floor), Danvers MA. The

know where I can get schematics,
documentation, etc? I will reim-
burse postage for all replies.

Kendall Stambaugh
5009 Guide Meridan
Bellingham WA 98225

I am trying to find a battery
backup for the S-100 bus. 1 need
one already built; however, a set
of plans will work as well.

Byron E. Parrish
Clipper Trading Co.

1718 Santa Fe Trail
Grand Prairie TX 75051

A friend and I are each buying
PETs with factory auxiliary cas-
sette tape storage. Over the years,
we have written BASIC programs
to run with our machines. The
problem is that we cannot figure
out how to efficiently convert our
OS Partitioned Data Sets into
cassette tapes to load into our
PETs. Typing these programs
manually from listings would be
too error prone and would take
forever. A friend suggested we
dump the program libraries on
seven- or nine-track IBM tapes.
We could then shop in software

club publishes a monthly news-
letter; for a free copy, write to
HUG Northshore, PO Box 112,
Danvers MA 01923.

Toronto Ontario

The Canadian Compucolor
User’s Group invites you to join
the group and utilize its growing
program library. For more infor-
mation, contact House of Com-
puters, Inc., 368 Eglinton Ave.
West, Toronto Ontario, Canada
M5N 1A2. 482-4336.

Washington DC

Washington Area KIM En-
thusiasts (WAKE) meet the third

houses that supplied cassettes for
someone to convert our tapes to
cassettes. Can anyone suggest
where we can get a list of compa-
nies or people to try, if the idea is
feasible, or, if it is not, suggest a
technique that will work.

Mitch Nadler
4283 Bedford Ave.

Brooklyn NY 11229

I have an E & L Instruments
MMD-1 microcomputer with an
MMD1/1 memory board. As an
exercise in digital design, I am
planning to add eight 2114s and
four 2708s, which I will interface
with the abovementioned units.
My problem is, 1 don’t know how
to go about designing the neces-
sary decoding circuits to drive the
memory ICs. Two areas on the
boards are labeled “decoding.”
How do the people who designed
the circuits come up with the par-
ticular memory decoding that is
used. Is there an E & L or other
publication dealing with this par-
ticular subject. If so, what do I
look for?

Gerald F. Gronson
28185 Alden
Madison Heights Ml 48071

Wednesday of each month, 7:30
pm, at the McGraw-Hill Con-
tinuing Education Center in DC.
For a copy of the current WAKE
newsletter, send an SASE to
WAKE, c/o Ted Beach, 5112
Williamsburg Blvd., Arlington
VA 22207. 538-2303.

Portland OR

Any Sorcerer user living in the
southwest Washington and great-
er Portland area is welcomed to
join the Portland Area Sorcerers
Users Group, which plans to pub-
lish a regular newsletter and hold
meetings. For further informa-
tion, contact either Timothy
Huang at 9529 N.E. Gertz Circle,
Portland OR 97211, 289-9135
(Mondays and nights); or Gary
Emmerson at 631 S.E. 41st, Apt.

CLUB NOTES

16 Microcomputing January 1980

43, Portland OR, 233-9684
(nights).

Akron OH

The Akron Digital Group pro-
vides tips on hardware and soft-
ware applications, and plans to
offer classes. The group meets the
fourth Wednesday of each
month, 7 pm, at the Kenmore
Public Library, 2200 14th St.

SW, Akron OH. For informa-
tion, contact Lon Laurich, 107
7th St. NW, Barberton OH
44203. 745-7819.

Hamilton Ontario

Inquiries concerning member-
ship in the Ontario Society for
Microcomputers in Education
(OSMIE) should be addressed to
N. Solntseff, Unit for Computer
Science, McMaster University,

Hamilton Ontario, Canada L8S
4K1 . OSMIE’s goal is to promote
the use of microcomputers in all
aspects of education.

Phoenix AZ

For $4 dues per year, you can
join the Arizona Computer
Society, PO Box 15623, Phoenix
AZ 85060. The society meets on
the first Tuesday of each month

at 8 pm, Rm. 209, DeVry Insti-
tute, 4702 N. 24th St., Phoenix.

Fairfield CA

The Solano TRS-80 User’s
Club (STUC) meets informally
every third Thursday at Owens-
Illinois, 2500 Huntington Drive,
Fairfield CA. Anyone interested
in getting STUC should contact
Dave or Steve Irwin at 422-3347.

LETTERS TO THE EDITOR

Oh-Oh

For October’s article winner I
vote for “Hurricane,” page 84.
This well-written article reflects a
thorough job of programming.
In fact, it is the first such article
written for the TRS-80 Level II
that actually ran in my machine
without modification . . . time-
ly, too, although Mr. Segar could
hardly have foreseen “Fred” at
the time he wrote and submitted
the article for publication.

I have one suggestion, which
you might like to pass on to your
authors. Some of us who have
been around for seventy, eighty
or more years don’t see fine de-
tails as we once did (I noticed it
particularly at the beach this sum-
mer), and that fine print you use
for the program listings is diffi-
cult for us at best. It’s like this.

The letter O and the figure 0
have been in use for quite a spell,
but even though I had three years
of schooling, until I started play-
ing around with computers I
never realized that a zero was
really nothing but a hungry O.

So, can you suggest that your
contributors avoid the use of the
letter O for variables? Maybe a D
or a Q? These latter could still
provide debugging experience,
but it wouldn’t be as boring.

A. R. Taylor
Gravette AR

I have received numerous let-
ters regarding my “Hurricane”
article and have been pleased re-
garding the “worked the first
time” comments. The “Hurri-
cane” program listing you pub-
lished is correct; however, I did
learn one valuable secret, which I

suggest you pass on to your fu-
ture authors. Never use the letter
O as a variable, especially when
using BASIC shorthand in a pro-
gram. When printed without the
slash, it is difficult, unless you
look closely, to tell the difference
between the letter O and zero.
One reader misinterpreted the
zeros in lines 200 and 201 for vari-
able Os. In doing so he complete-
ly changed the statement. I also
left out the THEN portion of the
IF/THEN statement. This is al-
lowable in Radio Shack Level II
BASIC shorthand and probably
also led to his confusion. Lines
200 and 201 are easier to under-
stand if written as follows:

200 IF L>0 THEN R=1

201 IF L<0 THEN R = 0

Without these lines, the program
definitely won’t work in all quad-
rants of the globe.

I discovered one other interest-
ing “quirk,” which I will pass on.
Although they look much alike,
the constant 1.5708 used in lines
310, 350 and 410 is not the same
as the constant 1.15708 used in
line 470. 1.5708 is used in the ra-
dian/degree conversion, while
1.15708 is used to convert nauti-
cal miles to statute miles.

Bryce D. Segar
Ft. Douglas UT

Scientific Applications

We hear more and more about
the business revolution caused by
the microcomputer. Magazines
such as Microcomputing are full
of articles on business applica-
tions and advertisements for
business-oriented systems. In-
deed, if we lightly read these pub-

lications we may get the impres-
sion that there are only three
types of microcomputer users: 1.
the hobbyist (a dying breed), who
sits in the garage and plays with
integrated circuits, but never real-
ly does anything with his
machine; 2. the “home computer
user,” who uses his computer as a
glorified video game, but has dif-
ficulty justifying it to his wife or
the neighbors; 3. the business
user, who uses the machine in his
business, but who has trouble get-
ting support from the manufac-
turers.

It sometimes seems that manu-
facturers and publishers are look-
ing forward to that great day in
the future when every mom-and-
pop-type drugstore will have a
computer in the back taking care
of sales, billing, inventory, pay-
roll and taxes. Since there are so
many small businesses in the
country, let’s make all the com-
puters to satisfy them, and just ig-
nore all the other users. They’re
only hobbyists or educators
(neither of whom have any
money), so they don’t matter.

I believe that the microcomput-
er manufacturers are overlooking
scientific applications. Scientists
and engineers are already among
the larger users of mainframes in
the U.S. today. A look at the
equipment manufacturers’ ads in
Physics Today will show that
about a third of the equipment
manufactured is something that
contains a dedicated micropro-
cessor. And scientists have
money to spend on equipment,
too.

Scientific computers ordinarily
perform three functions (two of
them not dissimilar to functions
performed by “business” com-
puters): analysis of data and stor-

age of information. We can use
text editing, too. The only real
point of difference between “sci-
entific” computers and “busi-
ness” computers is that scientists
like to use the machine for direct
data acquisition.

To my knowledge, the only
mainframe manufacturer seri-
ously addressing the problem of
the scientific user is Digital
Equipment Corporation. My own
microcomputer is an SWTP 6800
with 24K of memory, dot matrix
printer, Kansas City Standard
cassette interface and drive, 5
1/4” disk driver with DOS, plot-
ter, 256x256 graphics and an
8-channel, 8-bit ADC with a 50
microsecond conversion time. I
have half again the memory and
can load programs from cassette
three times as fast.

All this is the result of a cash
outlay of about $3000. If I were
to include the cost of my time for
construction of the graphics in-
terface and all of the program-
ming I had to do, it would prob-
ably raise that to about S7000.
But most of what I had to do was
reinvent several wheels.

Dr. Gordon W. Wolfe
Asst. Prof., Physics/ Astronomy
University of Mississippi

Epistolary Correspondence
on Polysyllabification

Well, I just read Mits Hadeishi’s
letter (November 1979), and I was
moved to write.

He’s right! What kind of a title
is “Microcomputing”? A lot of
people can’t even pronounce itl
What’s so bad about 1000 bits per
second? People didn’t understand

Microcomputing January 1980 17

Editor, KILOBAUD Microcomputing
Pine Street

Peterborough, NH 03458
Dear Sir:

I like

<ilobaud

Microcomputing

I also thought that having the complete table of contents
on the front cover was a fine idea.

You do a great job between the covers.

Sincerely,

L. Foster, Jr.

Instructor
Electronics Engineering Technology

it? So why change to something
more egregious?

73 has a good name. It’s related
to ham radio; it’s short and easy
to remember. Now we can do the
same thing here without changing
the name much — just call the
magazine “Kilo.” Remember:
Ease of recognition of a name
varies inversely with the number
of syllables.

I don’t care for the business-
boxy cover photos. They look
like U.S. Army tech manuals.
How about pictures of kids with
color graphics displays? Comput-
er graphics displays? Something
eye-catching? I think it looks bet-
ter not to have the table of con-
tents on the front; you have too
many articles for something that
important. However, the cover
picture could be related to one of
the articles inside. I think it’s a
good idea to have a thematic issue
now and then , but not very often.

Please bring back Kilobaud.
It’s hard to advertise your mag
(which is still the best) by word of
mouth when the title is mike-ko-
to-te-pring, or something like
that.

Richard A. Rodman
Vienna VA

Still More

Try the circuit in Fig. 1 with
David Morr’s TTY program (Au-
gust 1979 issue, p. 38).

John C. Rogers, Jr.
New Bedford MA

Ink Up and Start Typing

The article on the Centronics

779 Printer in the October 1979
issue was interesting and well
written. I have had a Centronics

780 printer for a little more than
one year now, and I have a tip I
would like to pass along. My 780
has the same ribbon assembly as
the Model 779. The only problem
I have ever had with the ribbon is
the short lifetime of the ink with-
in it. Ribbons are too expensive to

replace very often, so I came up
with a better solution.

For less than one dollar I
bought a bottle of ink for re-ink-
ing pads. Now when my ribbon
runs low on ink I simply apply
some more ink to the top edge of
the ribbon. I’m careful not to
soak the ribbon too much.

I continue printing until the
ribbon has made a complete pass
through the ribbon cartridge, and
then apply a little more ink to the
top of the ribbon since what was
on bottom is now on top. The
pinch rollers help distribute the
ink along the length of the ribbon
so that by the third pass, it is like
a new ribbon.

I have been using this method
on the same ribbon for about ten
months, and it currently shows
no sign of wear, though I do not
expect it to last forever.

By the way, does anyone else
out there have an F-8 micropro-
cessor system? Mine is called a
Termdisk (it contains an eight
inch floppy disk) and is manu-
factured by International Com-
puter Products in Dallas. It is a

capable system even though it
runs on an F-8. Anyone inter-
ested in F-8s, let me know. I
doubt Microcomputing will ever
print any articles on them.

Gary Fancher
204 Dee Lane
Arlington TX

Before we can print any F-8 arti-
cles, someone must write them.
How about you, Gary?— Editors.

Gobble, Gobble, Gobble

Murphy was an optimist.

Else, why would a typo creep
into Bill Harvey’s October 1979
article, page 99, second column,
third paragraph, where he is talk-
ing about his system. The typeset-
ter, not believing his eyes, in-
serted an n, erroneously produc-
ing the word “turnkey.” This is
obviously an error since the next
word is “home-built.”

Surely, everyone except the
typesetter knows that a turnkey
system is one bought complete
with all software and hardware,
in one package, usually for one
price, and most often for one par-
ticular application, ready to plug
in and start processing data. The
term probably stems from an
analogy to an automobile pur-
chase where you pay your money,
turn the key and drive away.

If the application is BASIC
programming, then some turnkey

Fig. 1.

systems are the PET, the TRS-80,
the Sorcerer and TI 99/4. But
there’s no way a “home-built”
system can be a turnkey system.
Obviously Mr. Harvey intended
it to read as follows: “turkey
home-built system.”

Now, don’t you understand?
Murphy was an optimist!

D. A. Bishop
Austin TX

Both the editor who worked on
the article, and the typesetter who
set it, are former prison guards
( who often had to restrain com-
pulsive crank-letter writers from
going berserk in the exercise yard
and trying to hoe messages to the
warden in the turf). Consequent-
ly, our editor and typesetter are
still imbued with prison parlance
and undoubtedly had their previ-
ous jobs in mind when they edited
and set the article. —Editors.

Port Alright

As you know, one of the great-
est obstacles to using a micro-
computer in a business applica-
tion is the lack of qualified hard-
ware repair specialists and soft-
ware consultants. I own a Sol
with a Helios IV disk drive and
have tried to obtain satisfactory
service in the Houston area for
several months — all to no avail.
The local PTC dealer (at least un-
til PTC’s recent demise) proved
to be totally incompetent and un-
professional.

A few weeks ago I noticed in
your magazine an advertisement
for Computer Port in Arlington
TX offering software for the Sol.
On a lark, I called them to find
out more, and as with all good
stories, there was a happy ending.

I was invited to their offices to
have my system repaired (it had
been down for 16 weeks at the lo-
cal dealer) and to consult with
them on my specific software
problems. In two days my entire
system was not only repaired, but
upgraded as well. Their service
department was remarkable in
that they were able to perform re-
pairs on both drives, which, ac-
cording to all information avail-
able in Houston, required service
in California.

I just though you might like to
know that there are some good
people around who support the
efforts and standards of your
magazine, and who can perform
the same.

Kenneth J. Edwards III
Houston TX

18 Microcomputing January 1980

Dealer Inquiries Invited

The Product. Only high quality, prime, burned-in and
tested 4116 16K dynamic RAMs. Don’t be caught
unaware! All TRS-80 memory expansion kits are not the
same. UHF Associates’ memory expansion gives you high
quality coupled with outstanding performance. And with
their fast 200 NS minimum access time (less CPU wait
states) UHF’s 4116 16K dynamic RAMs provide both
storage and speed that won’t disappoint you later down the
road.

The Price. 16K Memory Expansion Kit for either
computer (pre-programmed DIP shunts included) or
expansion interface, $95. More? 32K Kit for expansion
interface, $180. Most? 48K Kit for computer and expansion
interface, $265.

The Promise. “Thou shalt not wait, worry or fret.’’
You’ll get immediate post-paid delivery from in-stock
inventory. You’ll get a full 12 month warranty. That’s about
four times the warranty others offer. And for installation,
you’ll get UHF’s “goof-proof" instructions. All you’ll need is
a screwdriver and about 10 minutes.

□ 16K Kit with shunts (for computer) $ 95

□ 16K Kit (for expansion interface) $ 95

□ 32K Kit (for expansion interface) $180

□ 48K Kit (for computer and expansion interface) $265

California residents please add appropriate sales tax

j Name (print)

I Street

[ City State Zip

I □ I’ve enclosed a check or money order for $

. payable to UHF Associates.

• We honor: □ Master Charge □ VISA/BankAmericard

j Account #

I Expiration Date

J Signature

(required for charge card purchases)

n

i

i

i

i

i

i

i

i

i

i

i

i

i

i

i

i

j

t* U14

ItM/lUHF

ASSOCIATES j

90 Transport Avenue, #4
Rohnert Park, CA 94928
Call 707/584-7844

TRS-80 is a registered trade mark of Tandy Corporation.

NEW PRODUCTS

Edited by Dennis Brisson

Video Display Terminal

The InterTube. II Video Dis-
play Terminal has recently been
upgraded with the addition of a
new version of software — version
1.7— which enables several new
user-oriented editing features
such as erase-to-end-of-line and
page. Standard features of the In-
terTube include an upper and
lowercase character set on an
8x10 dot matrix, a full 24 line by
80 character screen; a status line
that displays the operating mode
of the terminal and a complete
ASCII typewriter-style keyboard
with an 18 key numeric pad. The
terminal includes a hooded dis-
play to cut down on glare and
give extra privacy. A wide band-
width monitor provides sharp im-
ages everywhere on the screen
with below-the-line character de-
scenders to make reading easier.
Price is $995.

Intertec Data Systems Corpo-
ration, 2300 Broad River Road,
Columbia SC 29210. Reader Ser-
vice number 121.

Smart CRT Terminal

The ADM-31 smart terminal
offers two full 1920 character
pages of display with indepen-
dent page characteristics of Pro-
tect, Write/protect, Program
mode and cursor retention. If the
operator changes to another
page, the attributes are automati-
cally stored in memory and are re-

called exactly as they were orig-
inally when the page is read-
dressed. The microprocessor-
based ADM-3 1 is completely self-
contained and comes equipped
with keyboard, control logic,
character generator, refresh
memory and interface. The ter-
minal’s keyboard is integrated
with main logic and can generate
a full 128 ASCII character set. A
numeric keypad is also included.

Full editing capabilities allow
the user to clear the screen, use a
destructive cursor for character
change, skip protected fields,
backspace, move up, down, re-
turn, home and new line. The
ADM-31 features a high-resolu-
tion, 12-inch diagonal display
screen with 24 lines of 80 charac-
ters in a 7 x9 dot matrix. Price is
$1450.

Lear Siegler, Inc. /Data Prod-
ucts Division, 714 N. Brook-
hurst, Anaheim CA 92803. Read-
er Service number SI 27.

32K RAM for the H8

The DG-32D is a 32K RAM
board for Heath H8 computers.
Designed to operate either with or
without the present static mem-
ory in the computer, the DG-32D
is ready to plug into the H8 and
use without additional wiring. It
consumes less than 6 Watts pow-
er. Features include: full compat-
ibility with current Heath periph-
erals, circuit protection to pre-
vent damage to memory output
buffers if two blocks are assigned
to the same address space, mem-

ory addressing controlled by DIP
switch and transparent refresh.
Price is $479, assembled, tested
and burned-in.

D-G Electronic Developments
Co., PO Box 1124, Denison TX
75020. Reader Service number
D70.

PET Graphic
Display Board

The K-1008A-P Visible Mem-
ory is a high-resolution graphic
display board that upgrades the
Commodore PET computer sys-
tem to permit high-resolution
graphics. During image update

there is no snow or visible inter-
ference. When not used for
graphics, the board serves as an
8K byte expansion memory,
doubling the 8K PET capacity.
K-1008-3C graphic software
($20) is also offered.

The display board puts up a
high-resolution matrix of 64,000
dots (320 wide x 200 high) and al-
lows control of the on/off state
of each dot individually and inde-
pendently. The board interfaces
to the PET with the K-1007A-1
bus adapter ($99) with easily de-
tached ribbon cable intercon-
nects. Without bus adapter, the
K-1008A-P can be used with
AIM-65, KIM-1 and SYM-1 com-
puters. The K-1005A-P expan-

y,: ; -

The InterTube II.

Upgrading the PET with the K-1008A-P.

20 Microcomputing January 1980

sion card file ($80) is optional.
Price is $243.

Micro Technology Unlimited,
PO Box 4596, Manchester NH
03108. Reader Service number
M44.

Apple II Joystick

The PAIA/ Apple II Joystick
Controller features plug-in com-
patibility with Apple II’s game
I/O connectors, precision-gim-
baled self-centering action and
case style and color consistent
with the Apple II. Other features
include front-panel trimmers for
x- and y-axis outputs and a capac-
itively activated closure to the
Apple II’s SWO input which oper-
ates with a finger’s touch of the
controller’s metal shaft. Closure
to Apple IPs SW1 input is acti-
vated with a standard push but-
ton. Price is $65.

PAIA Electronics, Inc., 1020
Wilshire Blvd., Oklahoma City
OK 73116. Reader Service num-
ber P9.

Double-Density
Floppy Disk Interface

The Tarbell Double-Density
Floppy Disk Interface enhances
existing disk storage capacities
with only minimum reconfigura-
tion of existing microcomputer
systems. The interface board is
supplied with the new BASIC In-
put/Output System (BIOS) soft-
ware for CP/M on single-density
diskette, permitting the user to in-
termix single- and double-density
diskettes. The Tarbell system
automatically determines whether

single or double density is in use.
As many as four drives, using
either single or double density,
can be selected.

The 8 inch Shugart -compatible
disk interface contains phase-lock
loop and write precompensation,
providing more reliable data
storage and recovery. The on-
board phantom bootstrap
PROM is disabled on completion
of the bootstrap operation, free-
ing all 64K of memory address
space for other use. Multi-user
operation is now possible. Ex-
tended addressing capability pro-
vides eight additional address
bits, allowing direct transfers to
and from any location within a 16
megabyte address range. Price is
$425.

Tarbell Electronics, 950
Dovlen Place, Suite B, Carson
CA 90746. Reader Service num-
ber Til.

S-100 6809 CPU Card

The MD-690b CPU card brings
the 6809 processor to the S-100
bus. This single-board computer
integrates I/O, RAM, PROM
cassette interface and other fea-
tures in a complete package for
instant use. With the MD-690b
you have your choice of two dif-
ferent monitor PROMs. MON-
BUG II provides the firmware
you need to interface to memory-
mapped video cards such as the
VB1-B and MicroDaSys’ full-
color, 80 x 24 ColorMaster video
card. RSBUG II enables the user
to interface directly to an RS-232
terminal using the board’s own
hardware.

Features include an on-card
2400 baud (Manchester encoded)/
300 baud (KC Standard) cassette

PAIA *s joystick for Apple II.

Tarbell* s double-density floppy disk interface.

Model 4609.

The MD-690b CPU card.

interface, IK static RAM, 10K
PROM space, RS-232 level shift-
ers, an interrupt-driven keyboard
input, 20 I/O lines, power-on re-
set, DMA capability, interrupt
handling and real-time clock.
Prices are $239 (kit) and $299 (as-
sembled and tested).

MicroDaSys, PO Box 36051,
Los Angeles CA 90036. Reader
Service number Ml 10.

Interface Board for
Apple and PET

The Model 4609 is a new pe-
ripheral interface board that is
compatible with Apple II and Su-
perkim microcomputers without
any special adapter unit, as well
as with the PET Commodore

unit, provided an adapter unit
called Expandamem has been in-
stalled in it. The board has provi-
sions for extended board area and
dual heavy-duty power buses be-
tween the DIP IC leads for easy,
short bus connections. The 4609
is designed for construction of
special control, communications,
peripheral or memory interface
circuits using support devices by
major semiconductor manufac-
turers, as well as for breadboard-
ing experimental circuits.

Three connectors, in addition
to the standard 25/50 system bus,
are available for input/output. A
20/40-contact card-edge connec-
tor, fabricated on the rear of the
board, mates with a 3-M-type rib-
bon connector. Alternatively, a
right-angle solder-tail header
may be positioned in this same lo-
cation. The Model 4609 also ac-

Microcomputing January 1980 21

The TNW-2000.

commodates the miniature SIP-
type connectors, which may be
placed on the periphery or in mid-
board. Price is $21.50.

Vector Electronic Co., Inc.,
12460 Gladstone Ave., Sylmar
CA 91342. Reader Service num-
ber V8.

with both the PET-style edge-
board connector and the
IEEE-488 standard ribbon con-
nector. Price is $229.

TNW Corporation, 3351 Han-
cock Street, San Diego CA 921 10.
Reader Service number T56.

The A 1-02.

Serial Interface

Now you can interface your
computer to standard RS-232
printers, terminals, modems and
other computers with the TNW-
2000 Serial Interface, which adds
a bidirectional RS-232 port to the
Commodore PET and other
IEEE-488 computers.

You can set the baud rate from
110 to 9600 bits per second and
switch-select the IEEE bus ad-
dress, data word length/parity
(8-bit words without parity or
7-bit words with even or odd
parity) ind operation with either
115 V or 230 V 50/60 Hz power
sources (power supplies are built
in). Enabling automatic conver-
sion between the (old style) PET
and ASCII character sets for both
input and output is also possible.

Other devices can be used on
the IEEE bus with the TNW-2000.
A 1 meter IEEE bus cable pro-
vides a daisy-chaining capability

TRS-80 Power Supply

Mayday is an uninterruptible
power supply that keeps your
computer on — and thus saves
your program and data from be-
ing lost — when the power fails. It
provides instant power switch-
over when a power outage occurs
and protects from any ac line
surges due to neighboring large
current changes. Especially de-
signed for the TRS-80, Mayday
can handle the complete business
system of video, expansion inter-
face, CPU and four disk drives
for about one-half hour of power
outage; nonbusiness systems will
hold for about one hour. It will
also handle other microcomput-
ers that have about 140 Watts
power consumption; 250 Watt
capability is also available.

Mayday maintains charge on
the standby battery during nor-
mal usage and is always ready for
use, no matter when the line
voltage fails. Accessories include

Mayday.

a battery and line surge protector.

Sun-Technology, Inc., Box
210, New Durham NH 03855.
Reader Service number S126.

Apple Analog Input Card

The AI-02 Analog Input Card
provides a single-card data acqui-
sition system for Apple II com-
puters. Sixteen analog channels
may be monitored by the system

with 8-bit resolution. Channels
are individually addressable, and
conversion time is 70 microsec-
onds. The system can be operated
from BASIC and also provides
interrupt capability for more effi-
cient software implementation.
The AI-02 is suited to such appli-
cations as temperature sensing
and process control.

Interactive Structures, Inc.,
Suite 204, 3401 Science Center,
Philadelphia PA 19104. Reader
Service number 149.

Also, see pages 188 and 189 for new software releases.

CONTEST!

Winner of the “best article of the month” for October is Allan J.
Domuret, author of “Expanded TRS-80 Operations.”

Winner of a lifetime subscription to Microcomputing is C. A.
Lopez of El Paso, Texas. Choice of a book from the Book Nook
goes to Saul G. Levy of Tucson, Arizona.

Congratulations to everyone.

One of your responsibilites, as a reader of Kilobaud MICRO-
COMPUTING, is to aid and abet the increasing of circulation
and advertising, both of which will bring you the same benefit: a
larger and even better magazine. You can help by encouraging
your friends to subscribe to Kilobaud MICROCOMPUTING. Re-
member: Subscriptions are guaranteed— money back if not de-
lighted, so no one can lose. You can also help by tearing out
one of the cards just inside the back cover and circling replies
you’d like to see: catalogs, spec sheets, etc. Advertisers put a
lot of trust in reader requests for information. To make it more
worth your while to send in the card, a drawing will be held each
month and the winner will get a lifetime subscription to
Kilobaud MICROCOMPUTING !

22 Microcomputing January 1980

6809 PROCESSING POWER!

The Percom SBC/9 . Only $199.95.

Fully compatible wi th 1 he SS-50
requiring no modification of
board, memory or 1/

SBC/9” is also a
board control
ROM operatin
peripheral ports and a full-range
clock generator.

Make the SBC/9” the heart of your computer and put to work
the most outstanding microprocessor available, the 6809.

the Mighty 6809

Featuring more addressing modes
than any other eight-bit processor,
position-independent coding, special
16-bit instructions, efficient argu-
ment-passing calls, autoincrement/
autodecrement and more, it’s no won-
der the 6809 has been called the ‘‘pro-
grammers dream machine.”

Moreover, with the 6809 you get a
microprocessor whose programs typ-
ically use only one-half to two-thirds as
much RAM space as required for 6800
systems, and run faster besides.

And to complement the extraordi-
nary 6809, the Percom design team
has developed PSYMON”, an extraor-
dinary 6809 operating system for the
SBC/9”

PSYMON” — Percom SYstem MONitor

Although PSYMON” includes a full
complement of operating system
commands and 15 externally callable

'trademark of Percom Data Company, Inc.

utilities, what really sets PSYMON”
apart is its easy hardware adaptability
and command extensibility.

For hardware interfacing, you
merely use simple, specific device
driver routines that reference a table of
parameters called a Device Control
Block (DCB). Using this technique, in-
terfacing routines are independent of
the operating system.

The basic PSYMON” command
repertoire may be readily enhanced or
modified. When PSYMON” first re-
ceives system control, it initializes its
RAM area, configures its console and
then ‘looks ahead’ for an optional sec-
ond ROM which you install in a socket
provided on the SBC/9” card. This
ROM contains your own routines that
may alter PSYMON” pointers and
either subtly or radically modify the
PSYMON” command set. If a second
ROM is not installed, control returns
immediately to PSYMON”

• Provision for multi-address, 8-bit bidirec-
tional parallel I/O data lines for interfac-
ing to devices such as an encoded
keyboard.

• A serial interface Reader Control output
for a cassette, tape punch/reader or simi-
lar device.

• An intelligent data bus: multi-level data
bus decoding that allows multiprocess-
ing and bus multiplexing of other bus
masters.

• Extended address line capability — ac-
commodating up to 16 megabytes of
memory — that does not disable the on-
board baud rate clock or require addi-
tional hardware in I/O slots.

• On-board devices which are fully de-
coded so that off-card devices may use
adjoining memory space.

• Fully buffered address, control and data
lines.

The SBC/9”, complete with PSYMON”in
ROM, IK of RAM and a comprehensive
users manual” costs just $199.95.

PERCOM DATA COMPANY. INC.

211 N KIRBY GARLAND. TEXAS 75042
(214)272-3421

v* P82

Percom peripherals for personal computing ’

To place an order or request additional literature
call toll-free 1-800-527-1592. For technical infor-
mation call (214] 272-3421 . Orders may be paid by
check, money order, COD or charged to a VISA or
Master Charge account. Texas residents must add
5°/o sales tax.

PRICES AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE

Welcome to Percom’s Wide World

Each LFD mini-disk storage system
includes:

drives with integral power
supplies in an enamel-finished
enclosure

• a controller/interface with ROM
operating system plus extra ROM
capacity

an interconnecting cable
r a comprehensive 80-page users
manual

Want

Percom LFD mini-disk drive
systems are supplied complete
and ready to plug in the moment
they arrive. You don’t even have
to buy extra memory. Moreover,
software support ranges from
assembly language program
development aids to high-speed
disk operating systems and
business application programs.

The LFD-400® and -400 EX® systems
and the LFD-800® and -800EX® systems
are available in 1-, 2- and 3-drive
configurations. The -400, -400EX drives
store 102K bytes of formatted data on
40-track disks, and data may be stored on
either surface of a disk. The -800, -800EX
drives store 200K bytes of formatted data
on 77-track disks.

The LFD- 1000® systems (not pictured)
have dual-drive units which store 800K
bytes on-line. The LFD-1000® controller
accommodates two drive systems so that
a user may have as much as 1.6M bytes
on-line.

Mini-disk storage system prices

1 -DRIVE
SYSTEM

2-DRIVE

SYSTEM

3-DRIVE

SYSTEM

MODEL

For the SS-50 Bus:
LFD-400®

LFD -800®

For the EXORciser* Bus:
LFD-400EX®
LFD-800EX®
LFD-1000®

$1399.95

2195.95

$ 649.95
945.95
(dual) $2495.00

$1049.95
1599.95
(quad) $4950.00

$1449.95

2245.95

EXORciser Bus LFD-400EX ® -800EX ® Systems

Data Terminal & Two-Cassette
interface — the CIS-30+

TIRM1NAI

LINE

AUTO

pebggm

• Interface to data terminal and two cassette recorders
with a unit only 1/10 the size of SWTP’s AC-30.

• Select 30, 60 or 120 bytes per second cassette
interfacing; 300, 600 or 1200 baud data terminal
interfacing.

• Optional mod kits make CIS-30+ work with any
microcomputer. (For MITS 680b, ask for Tech Memo
TM-CIS-30+-09.)

• KC Standard/Bi-Phase-M (double frequency) cassette
data encoding. Dependable self-clocking operation.

• Ordinary functions may be accomplished with 6800
Mikbug* monitor

Prices: Kit, $79.95; Assembled, $99.95. Prices include
a comprehensive instruction manual. Also available: Test
Cassette, Remote Control Kit (for program control of
recorders), 1C Socket Kit, MITS 680b mod documentation
and Universal Adapter Kit (converts CIS-30+ for use with
any computer).

Upgrade to 6809 Computing Power. Only $69.95

Although designed with the SWTP 6800 owner in
mind, this upgrade adapter may also be used with
most other 6800 and 6802 MPUs. The adapter is
supplied assembled and tested, and includes the
6809 1C, a crystal, other essential components and
user instructions. Restore your original system by
merely unplugging the adapter and a wire-jumpered

system is PSYM0N® (Percom SYstem MONitor),
the operating system for the Percom 6809
single-board computer. PSYM0N® on 2716 ROM
costs only $69.95. On diskette (source and object
files), only $29.95.

SS-50 Bus LFD -400- and LFD-800 M Systems

of 6800 Microcomputing.

6800/6809 SOFTWARE

System Software

6800 Symbolic Assembler — Specify assembly options
at time of assembly with this symbolic assembler. Source

listing on diskette $29.95

Super BASIC — a 1 2K extended random access disk BASIC
for the 6800 and 6809. Supports 44 commands and 31 func-
tions. Interprets programs written in both SWTP 8K BASIC
(versions 2.0, 2.2 & 2.3) and Super BASIC. Features: 9-digit
BCD arithmetic, Print Using and Linput commands, and much

more. Price $49.95

TOUCH UP 1 ® — Modifies TSC’s Text Editor and Text Pro-
cessor for Percom mini-disk drive operation. Supplied on

diskette complete with source listing $17.95

Operating Systems

INDEX® — This easy-to-use disk-operating and file man-
agement system for 6800 microcomputers is fast. I/O devices
are serviced by interrupt request. INDEX® accesses peripherals
the same as disk files — new devices may be added without
changing the operating system. Other features: unlimited
number of DOS commands may be added* over 60 system
entry points • display only those files at or above user-specified
file activity level* versions available for SWTP MF-68, Smoke’s

BFD-68 and Motorola’s EXORciser*. Price $99.95

MINIDOS-PLUSX® — An extension of the original
MINIDOS® for LFD-400® mini-disk systems, MINIDOS-

PLUSX® manipulates files by six-character names. Supports
up to 31 files. Resident commands include Initialize, Save,
Allocate, Load, Files (directory list), Rename and Delete.
Supplied on 2708 ROM with a minidiskette that includes
transient utilities such as Copy, Backup, Create, Pack and Print

Directory. Price $34.95.

PSYMON® — Percom SYstem MONitor for the Percom
single-board/SS-50-bus-compatible 6809 computer accom-
modates user’s application programs with any mix of peripher-
als without modifying programs. PSYMON® also features
character echoing to devices other than the communicating
device, sophisticated register and memory dump routines and

more. Price (on 2716 ROM) $69.95.

WIND EX® — Described in detail elsewhere on this page.
Business Programs

General Ledger — For 6800/6809 computers using Per-
com LFD mini-disk storage systems. Requires little or no
knowledge of bookkeeping because the operator is prompted
with non-technical questions during data entry. General Ledger
updates account balances immediately — in real time, and will
print financial statements immediately after journal entries. User
selects and assigns own account numbers; tailors financial
statements to firm’s particular needs. Provides audit trail. Runs
under Percom Super BASIC. Requires 24K bytes of RAM.
Supplied on minidiskette with a comprehensive users manual.

Price $199.95.

FINDER® — This general purpose data base manager is
written in Percom Super BASIC. Works wth 6800/6809 com-
puters using Percom LFD-400® mini-disk drive storage sys-
tems. FINDER® allows user to define and access records using
his own terminology — customize file structures to specific
needs. Basic commands are New, Change, Delete, Find and
Pack. Add up to three user-defined commands. FINDER plus
Super BASIC require 24K bytes of RAM. Supplied on minidisk-
ette with a users manual. Price $99.95

Mailing List Processor — Powerful search, sort, create
and update capability plus ability to store 700 addresses per
minidiskette make this list processor efficient and easy to use.
Runs under Percom Super BASIC. Requires 24K bytes of RAM.
Supplied on minidiskette with a users manual. Price $99.95.
From the Software Works
Development and debugging programs for 6800 nCs on disk-
ette:

Disassembler/ Source Generator $30.95

Reloc’tng Disas’mblr/ Segmented Text Gen $40.95

Disassembler/ Trace $25.95

Support Relocator Program $25.95

Relocating Assembler/ Linking Loader $55.95

SmithBUG** (2716 EPROM) $70.00

V 2 -Price Special on Hemenway Software!

CP/ 681: disk operating system $ 49.97

STRUBAL++ compiler $124.97

EDIT68 text editor $ 19.97

MACRO-Relocating Assembler $ 39.97

Linkage Editor (LNKEDT68) $ 24.97

Cross Reference utility $ 14.97

^trademark of Percom Data Company, Inc. ^ P7o

* trademark of Motorola Corporation
^Trademark of Hemenway Associates Company
* ’SmithBUG is a trademark of the Software Works Company

And ‘looking into’ is just what
you do with the Electric
Window® as you peer right
into memory space where
characters are being input
and manipulated. Display
is memory-resident,
programmable and generates
up to 24 80-character lines.
Other features include:

• standard character
generator plus provision for
optional special character
generator

• dual intensity, high-lighting
alphanumeric display

• scrolling by a programmable
register • programmable
display positioning

• programmable interlaced or
non-interlaced scan

• descenders on lower case
letters • users manual with
application instructions and
listing of WINDEX® driver.

The Electric Window.®

Worth Looking Into. $249.93'

WINDEX® is a fast video display driver program for
the Electric Window®. WINDEX® also features:
program and keyboard control of character
generators • displayable control characters — ■ under
program control • automatic scrolling • a driver
routine for the parallel input keyboard feature of the
Percom 6809 Single-Board Computer, the SBC/9®

• auto-linking to PSYMON®, the ROM operating
system for the SBC/9® • Prices: ROM version:
$39.95; LFD-400® compatible diskette (source and
object files): $29.95.

Now Available! the SBC/9 MPU/ Control Computer

(Single-Board-Computer/6809) — stands alone as a control computer, but also
compatible with the SS-50 bus for use as an MPU card. Includes PSYMON® (Percom
SYstem MONitor) in a IK ROM and provides for additional IK of ROM. Also includes IK
of RAM. Features: Super Port — provision for multi-address, 8-bit bidirectional data
lines • an intelligent data bus for multi-level data bus decoding • an on-board 110-baud
to 19.2 kbaud clock generator • extended address capability — to 16 megabytes —
without disabling baud clock or adding hardware. And much more. Supplied with

PSYMON® and comprehensive users manual. Price w $199.95.

See full page ad elsew here in this magaz ine for all of the SBC/9 ' features. '

Full Feature Prototyping PC Boards

All of the features needed for rapid,
straightforward circuit prototyping. Use
14- 16-, 24- and 40-pin DIP sockets
• SS-50 bus card accommodates 34- and
50-pin ribbon connectors on top edge,
10-pin Molex connector on side edge* 1/0
card accommodates 34-pin ribbon
connector and 12-pin Molex on top edge

SS-50 Bus Card: $24.95

• I/O card is 1-V4 inches higher than
SWTP 1/0 card* interdigitated power
conductors • contacts for power regulators
and distributed capacitance bypassing

• use wire wrap, wiring pencil or solder
wiring • tin-lead plating over 2-oz copper
conductors wets quickly, solders easily

• FR4-G10 epoxy-glass substrate.

w P73

To place an order or request additional literature call toll-
free 1-800-527-1592. For technical information call (214)
272-3421 . Orders may be paid by check, money order, COD or
charged to a VISA or Master Charge account. Texas residents
must add 5% sales tax.

PRICES AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE.

PERCOM DATA COMPANY, INC.

211 N, KIRBY GARLAND. TEXAS 75042
(214) 272-3421

Computer bulletin board services are everywhere. To join the fun of instant information ex-
change, you’ll need a terminal, a telephone and a modem (like the one described on p. 52).

Frank J. Derfler, Jr.

PO Box 17283
Montgomery AL 36117

T he hallways of companies in the
computer industry ring with
phrases such as “distributed process-
ing” and “smart terminals.” Mega-
dollar corporations are modifying
their management structures to take
advantage of the synergistic relation-
ship between computers and commu-
nications. Flashy executives and con-
gressmen too consider it a “perk”
(nontaxable) to be able to dial into
their mailboxes from a portable ter-
minal and sort through their old and
new messages. Military communica-
tions planners talk about many net-
work terminals sharing a “data base
in the sky.” There is no reason why
those of us with our own microcom-
puters cant participate in the exciting
world of digital information transfer
just like the megabuck boys.

Introduction

This is the start of a new Microcom-
puting feature called the Dial-up
Directory. The Dial-up Directory will
have two purposes: to provide (1) an
annotated directory of those comput-
er bulletin board services (CBBS) that
exist around the country and of those
individuals interested and capable of
exchanging data by phone and (2) in-
formation on software and systems
that can give you a dial-up capability.

We all have different interests and
ways of utilizing our computers.
Often our interests and requirements
are not shared by local individuals or
clubs. It is extremely helpful to be
able to share programs and sugges-
tions via data phone calls from
around the country.

<&— — =

We would like to publish
the name and phone
number of anyone
presently interested in
receiving data calls.

Whether your interests are graphics
on the Apple, games on the PET,
number crunching on the North Star
or computer- assisted instruction on
the TRS-80, there are others out there
similarly inclined. We will try to hook
you up.

We will have a lot of work to do
together. We will have to work out
and spread the word not only on elec-
tronic protocols, but also on those
human protocols that exist whenever
people interact with one another. We
will describe ideal ways of doing
things, the cheap way of doing things
and the road down the middle. First,
though, let’s describe the world we

will be looking at for those who may
not be familiar with it.

Getting Started

Almost all of the computers we own
have a practical communications ca-
pability of one sort or another. The
cassette recorder port on most ma-
chines is one example.

The main I/O capability we are in-
terested in is the RS-232 ASCII port
available either stock or as an ac-
cessory on almost every microcom-
puter. Cassette and disk formats may
differ between brands of computers
and, indeed, even between models of
the same brand, but the RS-232
ASCII port brings everything out in a
common electrical medium of ex-
change. My OSI can talk to your
TRS-80 at a useful speed, and we can
exchange programs and information
over a communications link.

Probably the best (but certainly not
the only) communications medium
we have between us is the telephone
line. The U.S. still has the best overall
phone system in the world (Japan and
some sections of the Middle East are
coming up fast), and the telephone
represents an economical way of
sending our minds out around the
country.

In order to convert and send the
digital plus and minus voltages of the
RS-232 signal over the phone lines, we
need a device called a modem, which
converts these dc voltages into audio

26 Microcomputing January 1980

From: EDST

EST /

CST /

MST /

PST HST

To GMT

CDST

MSDT

PDST

AST

Add: + 4

Hours

+ 5

+ 6

+ 7

+ 8 +10

Table 1. Conversion from local to Coordinated Universal Time (GMT).

tones. The tones are received by a
modem at the distant end and con-
verted back into dc. The Bell system
set the standards for low-speed (to 300
baud) modems; their Bell 103A stan-
dard is typically used. Under this
standard, each party (one called the
“originate” and one called the
“answer”) uses a different set of tones.

This means that if I wanted to call
you to send you the nifty program
that I just wrote to water my vegeta-
ble garden, we would first have to
verbally agree on the speed (110 and
300 baud are the most common) and
on which one of us would use the
originate signaling tones and which
one would use the answer tones. Then
we would connect our modems to our
phones and send data.

Obviously, one of us would have to
have a modem capable of operating in
the answer mode. This is important,
because as you read modem ads you
should look for the capability you
need. Many modems are originate on-
ly. Many others advertise themselves
as originate/ answer but don’t make it
clear that the option requires exten-
sive rewiring. “Switchable originate/
answer” is the key phrase for complete
flexibility.

Potential Difficulties

Establishing contact by phone
probably only means you are over the
hardware hurdle. Another favorite
buzz phrase in large system procure-
ment today is that hardware is easy
. . . it’s software that’s difficult.
Once you receive my data on your sys-
tem, what can you do with it? With
the right software, your system can
save it on disk or tape to recall and use
again at your convenience. We will
talk about software to do that in
future articles.

Without the right software, you
can only print out the data you re-
ceive. But at least you have a hard
copy to refer to. If your computer acts
only as a “dumb terminal,” then you
can probably have a nice chat, but
you may have only a few scribbled
notes to remember it by.

Other difficulties may be thrown
into our exchange of data if I am not
free to get on the phone at the same
time you are. There are two ways
around this: an auto answer capabili-
ty to allow access with the terminal
unmanned (after all, what good is
automation if you can’t put yourself
out of a job?) and a store and forward
service.

These services exist in many places
around the country. They are typical-
ly known under the generic name of
computer bulletin board services
(CBBS). I can dial into this service
(actually, anybody’s system with an
automatic answer modem, the right
program, sufficient memory and a
large electric bill) , select the bulletins
I want to read and leave a copy of my
rutabaga- watering program.

In that way, you and everybody
else on the system can review my pro-
gram at your convenience. This is
practically the ideal information ex-
change. Would you like to take part?
That is the goal of this series.

The Directory

We would like to publish the name
(use a pseudonym if you like, but no
CB call signs, please) and phone num-
ber of anyone presently capable of
and interested in receiving data calls.
We will need any specifics or limita-
tions, such as baud rate, answer only,
special control codes or carriage re-
turns. We need to know when and on
what days you will be interested in re-
ceiving calls. We will also have room
for information on interests — stock
market analysis, for example.

One of our biggest services can be
getting people with similar interests in
touch with each other — digitally. Be-
cause of the various time zones in-

volved, I suggest we use Coordinated
Universal Time (also known as GMT,
Zulu or WWV time). A quick- refer-
ence GMT-to-local-time conversion
chart is included in Table 1.

Remember: You may be getting
calls from around the country, so it is
only common courtesy to keep your
5-year-old from answering the phone
during the times you specified, and it
might be nice to not answer at all if
you are not interested or able to trans-
fer data on a specific day. A firm
promise to return the call at another
time is probably the least you owe
someone who called you in good
faith. An automatic audio answering
device such as a Code-a-phone will
allow recording up to 30 seconds of re-
ceived data. We’ll also discuss trans-
ferring data from the Code-a-phone
to the computer in a later article.

In this introductory article, let me
acquaint you with three excellent
computer bulletin board services (see
Directory). They represent a good
starting point because they each con-
tain extensive prompts and guides to
make your telecommunications trials
less terrifying. They are all available
24 hours a day, work either 110 or 300
baud and operate in the answer
mode. They are free of any financial
charge and don’t need any passwords
or codes, but that can all change if
they are abused. The rules are just like
those for a campground: keep it
clean, don’t leave any garbage behind
and don’t overstay your welcome,
because others are waiting to use the
facilities.

You can enter any of these systems
by dialing the phone number, con-
necting your modem as soon as you
hear the answering tones begin and
sending at least three carriage
returns. The host computer will read
the carriage returns and reply at the
proper speed. It is then that the fun
begins.

Let me hear from you if you want to
receive data calls or if you operate a
CBBS. Send mail to PO Box 17283,
Montgomery AL 36117, or leave a
message on the Atlanta CBBS (404)
939-1520. ■

Location

Operated by

Phone

Dallas

Ric Martin and Bill Kennedy

(214) 641-8759

Atlanta

Les Freed

(404) 939-1520

Oregon

Jim Willing and Bill Marx

(503) 646-5510

Dial-up Directory.

Microcomputing January 1980 27

Tiny Dual-Trace Oscilloscope

The micro-sized NLS MS215 scope is for microcomputer troubleshooting.

Nat Wadsworth
PO Box 3153
Milford CT 06460

I purchased my NLS MS215
dual trace oscilloscope at a
local electronics distributor. It
was in its original factory car-
ton, which I opened at the
distributor’s counter to make
sure that it came with probes. (It
did, but with simple alligator
clips at the working end!) I was
unsure whether probes were in-
cluded with the basic unit
because some of the advertise-
ments by mail-order suppliers
indicated that scope probes
were extra. The extra probes
referred to in some ads, it turns
out, are the fancy 10:1 probes
many people like to use.

I also gave the unit a once-
over glance while at the dis-
tributor’s counter. However, I
did not attempt to operate the
unit at the point of purchase.

Inspection

When I got the unit home, I
gave it a thorough visual inspec-

tion. The only physical defect I
could find was a tiny chip on one
of the corners of a front panel
slide switch. The flaw was big
enough to notice but not suffi-
cient to upset me. I don’t think I
would have passed the unit with
such a defect if I were the qual-
ity-control man at the factory.
On the other hand, I could under-
stand a weary inspector missing
the flaw if he or she had to ex-
amine hundreds of units per day
as they came down the produc-
tion line. After all, I had not
noticed the imperfection during
my once-over glance when I pur-
chased the unit.

I was pleased with what I
found in the manual. It is well
written and sufficiently compre-
hensive. The 36-page booklet
does a creditable job covering
the basic aspects of how to use-
the instrument, discusses the
theory of operation of the cir-
cuits used in the scope and
describes calibration and main-
tenance procedures. This is all
done on a much more thorough
level than in the manuals for
other pieces of gear that I have
had the occasion to examine
lately. The manual even in-
cludes a full schematic, printed

circuit board pictorials that in-
clude call-outs of active com-
ponents and troubleshooting
hints for each major section of
the instrument’s circuitry!

Power up

Time to turn the unit on and
try it out. The instruction
manual said to be sure the
batteries were charged up first
or else to run the scope off its ac
adapter. I plugged in the adapter
and gave it a few minutes to get
some initial juice into its bat-
teries per the manual’s recom-
mendations. Finally, it was time
to turn the unit on.

After powering it up, I noticed
an extremely high-pitched
whistling noise. It was faint but
clearly discernible. My first
thoughts were that it might drive
some people, particularly those
sensitive to high-frequency
sounds, slightly berserk. For-
tunately, the sound is indeed
very faint. I was alone in a com-
pletely quiet room when I first
turned on the unit. Subsequent
use has shown that just a slight
amount of ambient noise, such
as a softly playing radio, drowns
out the high-pitched sound that
emanates from the scope. The

noise apparently comes from
the unit’s power supply that
utilizes digital switching tech-
niques operating at frequencies
that are barely detectable by
people. (It may be interesting to
see how a dog reacts to the unit.
They apparently can hear higher
frequencies than people, much
more clearly.)

I also noticed that the scope
trace was tilted. When viewed
against the etched reference
grid on the unit, the trace was
about one-quarter of an inch
higher at the left side of the dis-
play than at the right side. To
me, there are few things more
annoying when trying to read a
scope than having the display
run downhill (or any way but
straight) across the display
tube! It is disorienting, to say
the least, and it makes it tough
to do any kind of serious voltage
measurements.

I can assure you I was not
pleased with what I initially saw.
I don’t know if the particular unit
I purchased left the factory in
that condition. I certainly hope
not. Perhaps jarring the unit dur-
ing shipping caused the cath-
ode ray tube to rotate slightly. In
either case, the company might
want to keep an eye on the prob-
lem. I don’t think mine was an
isolated case. I recently noted
the same firm’s model 15 scope
on display at an electronics
show. The signal being dis-
played was tilted in a notice-
able manner. I wonder how
many prospective customers
were turned off.

It turns out that it is fairly sim-
ple to correct such a situation.
The problem comes about from
the cathode ray tube not being
positioned correctly. Undoing a
screw on the instrument’s case
permits the cabinet to be slid

This front view of the MS215 shows that all the essential controls are right up front where needed.
28 Microcomputing January 1980

off. Doing so reveals the com-
pact and neatly laid-out cir-
cuitry.

The miniature cathode ray
tube is held at its base by a
socket, which is mounted in a
clamping arrangement. A single
screw on the socket clamp ap-
plies pressure to the clamping
mechanism that holds the
socket. Backing off the screw
allows the tube socket to be
rotated, and the display can
thus be adjusted so that a
straight raster line runs hori-
zontally.

After adjustment, retighten
the clamping screw. The adjust-
ment takes just a few minutes;
however, it is annoying to have
to do it. After all, the display is
the essence of an oscilloscope. I
think the factory would want to
pay close attention to see that it
was OK when shipped and that
it stayed properly oriented dur-
ing shipment. In all other
respects the unit is fine. In fact,
the little scope is ideal for my
applications.

Specifications

While I did not make tests
with precision equipment, it
appeared that the equipment
was within specifications. How-
ever, some of the specifications
stated seemed to be merely an
exercise in “specmanship.”

For instance, the vertical
calibration is stated to be within
three percent of full scale. Full
scale on this little scope is all of
one inch. That means that if you
are trying to measure a voltage
that is one volt peak-to-peak, on
a full-scale setting, the vertical
distance might vary by three
one-hundredths of an inch. Not
many people can readily discern
that difference on an oscil-
loscope of this size. . . nor
should they try to!

Most of my work is with dig-
ital logic in microcomputer
systems. Occasionally I need to
check analog signals, such as
when checking power supplies,
A/D or D/A converters; and, once
in a while, I will check out a radio
or audio system. Being a dual
trace oscilloscope, the MS215,
is a real boon to me. I can put a
system clock signal on one
trace. I can then use the other
trace to follow a signal path

A top view of the MS215 circuit board. CRT tube and batteries have
been removed for this photo. Arrow points to rear mounting bracket
for the CRT tube. Loosening a single screw on this bracket allows
the CRT tube to be rotated slightly to correct a tilted display if
necessary.

through a logic network and
check it directly against the
system clock. Misbehaving
counters, shift registers and just
plain logic gates can’t escape
detection using this method.

The vertical sensitivity on
each channel can be selected to
be anywhere from 10 millivolts
per division to 50 volts per divi-
sion. This sensitivity selection is
independent on each channel. It
is set through a pair of switches.
A four-position slide switch
selects a sensitivity of 0.01, 0.1,
1.0 and 10 volts per division. A
three-position toggle switch
multiplies the slide switch
selection by a factor of 1, 2 or 5.
Additionally, a vernier knob
allows the sensitivity to be con-
tinuously varied between set-
tings of the switches if desired.
When the vernier knob is placed
in the CAL position, the sen-
sitivity is specified to be within
three percent of the switch set-
tings.

If you are making critical volt-
age measurements, it is gen-
erally necessary to re-zero the
scope trace each time the sen-
sitivity setting on a channel is
changed. This is readily ac-
complished by placing the chan-
nel’s mode select switch into its
center GND position and then
tweaking the vertical position
knob to set the trace at the
desired zero-reference level on
the display graticule.

The horizontal sweep rate can
be selected to be anywhere from
0.5 second per division to 0.1
microsecond per division.
Again, a vernier knob allows
calibrated operation or any
speed between the switch set-
tings in an uncalibrated fashion.

The horizontal sweep can be
initiated by an external signal, by
a signal being displayed, at a rate
synchronous with the 60 cycle
line frequency if the unit is being
run from an ac line source, or the
sweep can be placed in a free-
running mode. The free-running
mode gives a continuous dis-
play regardless of what a signal
is doing, and is thus useful for
viewing the voltage levels of
essentially steady-state signals.
This is a feature that is conve-
nient to have when tracing logic
levels through a series of static
gates.

Mode of Operation

The scope can display a
signal on channel one by itself,
on channel two by itself, or it
can display two signals simul-
taneously in either the so-called
“chop” or “alternate” modes.

In the alternate mode, the
scope shows one sweep of the
signal on channel one, the next
sweep on channel two and so
forth. That is, it continuously
alternates between displaying
the two signals. The rate at
which it alternates essentially
depends on the horizontal
sweep rate that has been select-
ed by the operator. Of course,
when the sweep rate is rapid
enough, the two channels ap-
pear to be constantly displayed
due to the latent image
mechanism of the human eye.

In the chop mode, the oscil-
loscope also alternately dis-
plays the signals, only now the
alternating is done at a fixed
rate regardless of the settings of
the horizontal sweep switches.
This mode is fine for viewing
signals that are relatively low in
frequency, i.e., signals that are
below approximately 20,000
cycles per second. Above that
rate you are likely to observe
gaps in the signals being dis-
played as the scope alternates
between the two signals. (Of

course, that doesn’t present any
problem. It means you just
switch over to the alternate
mode of operation because
signals requiring that rate of
speed on the horizontal sweep
will be fast enough to give a
solid appearance in the alter-
nate mode!)

You can adjust the triggering
point of a signal being displayed
so that the sweep starts on a
negative or positive portion. You
can even select the signal level
at which triggering is to occur. I
found the internal triggering
capability of the scope to be
quite good as long as the signal
varied over about two vertical
divisions or more. The manual
says that at least one division of
deflection is required to get
reliable internal triggering. My
scope will indeed trigger on
signals at that level, but it is dif-
ficult to select a particular point
on a signal when the deflection
is that low. At two or more ver-
tical divisions I find I can get
good triggering control at points
that I desire on most waveforms.

Other Features

You also have the option of
using the XY mode. In this mode
the horizontal sweep is con-
trolled by an external signal of
your choosing, instead of an

Microcomputing January 1980 29

The NLS model MS215 weighs three pounds and is easily carried in
one hand. (Photos courtesy of Non-Linear Systems, Inc., Del Mar CA
92014)

internal time base. This feature
is necessary to satisfy all those
people who want to look at
Lissajous patterns or do TV vec-
tor analysis and so forth.

Would you believe this little
scope even has a built-in one
volt peak-to-peak square wave
calibrating signal? This feature
is convenient, especially when a
signal you are tracing suddenly
disappears and you want to
quickly make sure that the

scope itself hasn’t gone on the
blink! (Isn’t it amazing how we
always question the perfor-
mance of the test equipment we
are using even though we know
that the piece of gear we are us-
ing it on is not working in the
correct fashion?)

This small, compact scope is
also able to operate from its
own internal batteries. It is
simply fantastic! I can’t count
the number of times, prior to ob-

taining this scope, that I have
wanted to check something out
in an electronic gadget, only to
be stopped by the inconve-
nience of not having a portable
scope. Who wants to lug a 30
pound oscilloscope out to the
garage, connect two or three
extension cords in series and
then try to work on a car radio in
the front seat while trying to
peer into the back seat to ob-
serve a scope trace?

Have you ever been working
on a piece of digital circuitry on
your bench and come to the con-
clusion that your logic probe
alone wasn’t going to solve the
problem? Then, have you noted
that every ac receptacle on your
bench was in use (out of neces-
sity, of course) and yet your
oscilloscope was not plugged
in? In order to be able to plug in
your scope, you have to unplug
your soldering iron. And then, as
soon as you have done that, just
after the soldering iron has
cooled down, you find that you
have to solder or unsolder a con-
nection in order to make further

tests! Frustrating, isn’t it?

You won’t have those prob-
lems if you have an MS215! You
can pick this little three pound
beauty up in one hand, forget all
the extension cords, run out to
the garage and place it right on
the front seat beside the radio
you are working on— so you can
probe circuits and view the
results without straining your
neck! You have three hours of
scope operating time available
when in the battery mode of
operation. Since the scope is
solid-state and has essentially
“instant-on” capability, you can
turn the scope off when not ac-
tually taking measurements.
Thus, you can work practically
all day in an isolated environ-
ment without needing any ac
power.

All in all, I am favorably im-
pressed by the NLS MS215 dual
trace scope. I have not seen
anything to match it in its price
class (about $430 at the time of
this writing). The closest com-
petition I have seen or heard of
is well over twice its price. ■

n/iAE5Ann r "

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30 Microcomputing January 1980

Master Charge or Visa card holders:
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Here’s another way to employ the Sorcerer’s user-defined graphics keys.

Timothy Huang
9529 NE Gertz Circle
Portland OR 97233

T here are two major reasons
why I chose the Sorcerer mi-
crocomputer rather than others.
First, it has the interchangeable
ROM language pack, which I
can plug, unplug or exchange to
another language in seconds.
No other systems have yet been

able to come close to this ad-
vantage. For example, with the
Apple or the Radio Shack
TRS-80, once the language firm-
ware is installed, you are stuck
with it, like it or not. It is almost,
but not quite, impossible to
change them. However, we (the
users of Sorcerer) should re-
mind Exidy that if they cannot
provide other languages sooner,
there will be a lot of complaints.

Are you listening, Exidy?

The second reason I chose
the Sorcerer was its user-de-
fined graphics keys, which are
not shown in other systems. If
you are thinking of getting into
graphics, and your system does
not provide this feature, then
you will have to spend more
money to buy disks and pro-
grams (as with the Apple II).

Once, when I was in a down-

town Portland computer-
camera store (I am a shutterbug,
too), the salesman tried to sell
me an Apple computer. He said
that his store conducted a six
month’s market research before
deciding to sell the Apple. He
put a disk into the machine and
showed me all the magic
graphics on the screen. He al-
most believed that I was sold.
But after he learned that I al-
ready had a 32K Sorcerer, his at-
titude changed 180 degrees. He
scoffed, “You spent more than a
thousand bucks for that?” He
then offered to trade an Apple
for my system.

I was surprised, not only at
his bad sales approach, but also
his ignorance. Despite the six
month’s study, he missed the
great features of the Sorcerer.
By the way, I an not criticizing
the Apple, but rather that sales-
man and the store owner.

The Sorcerer as a Ping-Pong
Diplomat

The instruction manuals that
come with the Sorcerer tell you
how to use the user-defined
graphics. If you happen to be
Japanese, you can put the entire

♦ t I t J i

U-i

RSA+A^fl + 0

if - % t> $ $

Photo 1. Chinese characters on the Sorcerer.

32 Microcomputing January 1980

Japanese alphabet into it, and
then type (or print out) a letter
to your loved ones. The Sorcerer
also accommodates all other
alphabetical languages.

But I am neither Japanese nor
a Yankee; I am Chinese. “Oh,
well,” as you Yankees would
say, “the Chinese don’t use the
alphabet. Besides, they read
and write backwards.” True, we
do not use the alphabet, but in-
stead we use two-dimensional
(square) graphical characters.
According to scientists, the hu-
man eye can accept a pictorial
message easier than a linear
one. Besides, a quarter of the
world’s population is doing it.

However, we all paid a higher
price for this precious cultural
gem: We spent considerable
time just learning and practicing
to write the characters. For each
character, each stroke, se-
quence and even every dot
should be placed exactly right.
No mistakes are allowed; other-
wise you may end up expressing
just the opposite of what you
meant. Because of its unique
features, we also don’t have
portable typewriters for our lan-
guage. Let me tell you about the
typewriter used in Taiwan, my
homeland.

Typing a letter requires using
a box about 2 feet by 2 feet con-
taining about 2000 types, each
with an imprinted character. The
operator has to move a drum to
the desired character position
and press at the bottom to trig-
ger the pick-up-and-hit-the-paper

mechanism. Just think how
heavy 2000 lead-antimony-tin
alloy types are. Maybe this is
why there are no portable type-
writers for the Chinese lan-
guage; they would sacrifice the
beautiful calligraphy.

My parents always said my
handwriting was so terrible that
they could not read my letters.
So I made up my mind to give my
parents, and the Chinese peo-
ple, a good solution: a portable
Chinese typewriter!

Sorcerer helped me to bring
that dream one step closer to
my long-desired goal. After
tinkering with the machine for a
while, I discovered (if the people
at Exidy have not already ac-
complished this) a way to define
the graphics keys without using
the monitor program. With the
BASIC language, you can define
the desired graphics and save
them with your main program
without first loading the
graphics through the monitor
and doing your program through
the BASIC. Plus, you can
change the graphics within your
BASIC language. This really
simplifies the process.

Changing the Graphics

1. You still have to use the
section paper to draw your
graphics symbols.

2. Add up the numbers by
decimal, not hex. The rightmost
column is 1. Each subsequent
column to the left is doubled.
The leftmost column is 128. See
Fig. 1.

126

64

32

16

8

4

2 1

1

zrr

2

3

4

5

|

6

7

8

HEX

DECIM)

OO

O

38

56

44

68

82

130

82

130

44

68

28

40

EE

238

Fig. 1.8x8 dot matrix and data for Q.

100

READ A

200

FOR J » 1 TO 8

250

READ B

300

POKE (W + J) ,B

400

NEXT J

500

POKE A,N

600

DATA 3888,0,56,68,130,130,68,40,238

700

END

Program 1. BASIC program to define graphic symbol Q.

3. See Program 1 to put Q onto
the screen: In line 300, W + J
values should be equal to the
memory addresses (eight bytes).
If you want to put Q into key 192
(!key), then let W= -513. For
the 193 key (’’key), let W = - 505,
etc. In line 500, A is the position
that you want this graphic to be

placed on the screen; N is the
key number. (Try key 192; you
will see the omega sign.) If you
do not use POKE you can use
the PRINT statement(s) to print
it out. If so, you should omit the
first number (3888) in line 600.
Also, scratch line 100.

4. Make sure all the numbers

150 FOR X = 1 TO 30 : PRINT : NEXT
160 N = 0
170 RESTORE

180 W = 1025 : 0 = 128 : P = 129 : Q * 130 : R = 131
200 IF N = 32 GOTO 160
250 GOTO 500
260 N = N + 1

270 W = W -32 :0 = 0 + 4:P = P + 4 : Q = Q + 4 : R = R + ^

280 GOTO 200

500 READ A

510 FOR J = 1 TO 32

520 READ B

530 POKE ( J - W ), B
540 NEXT J

550 P0KE-A , 0 : POKE ( 1 -A) , P : POKE (64-A) ,Q:P0KE (65-A) ,R
560 GOTO 260

1080 DATA3888, 0,1 ,1 ,1 ,1 ,31 ,17,17,0,0,0,0,240,16,16,17,17,31
1082 DATA1 ,1 ,1 ,1,0,16,16,240,0,0,0,0,0

1100 DATA3884, 2,1 ,0,0,127,16,16,8,0,0,128,0,252,16,16,32,8,4,2
1102 DATA1 ,2,4,24,0,32,64,128,0,128,64,48,0
1120 DATA3880,0,32,32,249,34,248, 169, 170,32,80, 136,4,250,0, 196
1122 DATA84, 251 ,170, 170,251 ,34,250,32,0,212,84,84,212,68,68,76,0
1140 DATA3870,0,1 ,1,17,17,17,31.1,0.0.0,16,16,16,240,0,1,33,33,33
1142 DATA 63 ,0,0, 0,0, 8 , 8 , 8 , 248 ,0,0,0

1160 DATA 3872 ,0,0,0,7,0,0,31 ,0,0,0,0,192,0,0,240,0,1,5,9,17,33
1162 DATA5, 7, 0,0, 64, 32, 16, 8 , 0,0,0

1180 DATA3868, 32, 121 ,137,0, 16,255,16,255,128,240,64,64,0,0,124,68
1182 DATA1 46, 255, 146, 255, 16, 255, 16, 0,68, 68, 72, 80, 65, 65, 126,0
1810 DATA361 4, 8, 8, 63 , 8, 15,0, 127,0,32,32,248,32,224,0,252,0,63,33
1812 DATA 63 , 33 , 63 , 4, 56 , 0,248, 8 , 248, 8 , 248, 64, 56,0
1830 DATA3610.0, 1,1 ,1 ,1 ,63,1 ,1 ,0,0,0,0,0,248,0,0,2,4,8,16,32,64,0
1832 DATA0, 128,64,32, 16,8,4,0,0

1850 DATA3606, 0,0, 0,0, 0,0, 0,1 27, 0,0, 0,0, 0,0, 0,252, 0,0, 0,0, 0,0, 0,0
1852 DATA0, 0,0, 0,0, 0,0,0

1870 DATA3602,1 ,2,4,9,23,36,71 ,132,0,130,66,34,202,74,202,74,7,4,4
1872 DATA1 1,10,18,35,0,202,10,2,226,34,42,228,0

1880 DATA3600, 8, 8, 16, 49, 82, 148, 16, 16, 64, 64, 128, 0,254, 64, 64, 120, 16, 16
1882 DATA1 6, 16, 16, 16, 16, 16, 64, 64, 124,64,64,64,64,0
2140 DATA3484, 0,0, 31 ,16,16,31 ,16.31 .0,0,248,8,8,248,128,252,32,32
2 1 42 DATA32 ,34,36,40,48,0,128,128,64,32,16,10,4,0
2150 DATA3482, 255, 128, 129, 191 ,129,9,189,165,254,2,2,250,2,2,18,18
2152 DATA1 64, 189, 128, 188, 129, 128, 255, 0,1 46, 162, 66, 170, 18, 2, 254,0
2160 DATA3480, 0,0, 8, 7, 0,0, 63, 0,0, 0,0, 224, 0,0, 248, 0,2, 4, 8, 16,32,64
2162 DATA0, 0,1 28, 64, 32, 16, 8, 4, 0,0

2170 DATA3478,0,1 ,1 ,1 ,1 ,1 ,1 ,1 ,63,0,0,0,0,0,0,0,248,1 ,1 ,1 ,1 ,1 ,1 ,1 ,0
2172 DATA0, 0,0, 0,0, 0,0,0

2180 DATA3476, 0,0, 0,3, 0,0, 2, 2, 0,0, 0,192, 64, 64, 64, 64, 4, 8, 16, 32
2182 DATA64, 0,0, 0,32, 16,8,4,2,0,0,0

2190 DATA3474.8, 16,47,65, 129,31 ,17,17,0,0,224,0,0,240,0,0,127,1
2192 DATA1 ,1 ,1 ,1, 1 ,0,248,0,0,0,0,0,0,0

2200 DATA3472, 0,0, 8, 7, 0,0, 63, 0,0, 0,0, 224, 0,0, 248, 0,2, 4, 8, 16, 32, 64
2202 DATA0, 0,1 28, 64, 32, 16, 8, 4, 0,0

2210 DATA 3470,7,4,4,4,7,4,4,4,224,32,32,32,224,32,32,32,7,4,4,4
2212 DATA8, 8, 16,0,224,32,32,32,32,32,96,0

2220 DATA3468, 0,1 ,1 ,1 ,1 ,1 ,1 ,63,0,0,0,0,0,0,0,248,1 ,1 ,1 ,1 ,1 ,1,1 ,0
2222 DATA0, 0,0, 0,0, 0,0,0

2230 DATA3466,0,0,7,8,8,8,8, 1 1 ,0,0,240, 16,16,16, 16,208,8,8,8,8,7
2232 DATA0, 0,0, 16, 16, 16, 16,240,0,0,0

2650 DATA3254, 17,37,69.151 ,32,64,175,32,0,70,68,200,30,34,212,8
2652 DATA39, 36, 36, 36, 36, 40, 32, 0,1 36 , 148, 148,162,162, 128,96,0
2660 DATA3252,31 ,1 ,127,65,85,85,65,0,240,0,252,4,84,84,4,0,63,33
2662 DATA 63 , 33,63, 1 ,1,0,248,8,248,2,254,0

2670 DATA3250, 0,57, 74, 73, 72, 120, 72, 72, 146, 36, 72, 36, 146, 0,64, 128

2672 DATA73, 123, 73, 73, 137, 137,1 ,0.254,2,74,82,34,90,254,0

2680 DATA3248, 16,16,32,64,129,124,68,68,32,32,64,128,0,254,2,2,68

2682 DATA76, 84, 100,68,68,124,0,66,34,34, 18,4,100,24,0

2690 DATA3246, 0,0, 0,0, 0,1 27, 8, 8, 0,1 6, 16, 16, 254, 18, 18, 18, 8, 8, 8, 255

2692 DATA0,0,1 ,0,34,34,34,162,68,84,136,0

2700 DATA3244, 31, 17, 17, 17, 31, 17, 17, 17, 240, 16, 16, 16, 240, 16, 16, 16

2702 DATA31 ,17,17,33,33,65,0,0,240,16,16,16,16,48,0,0

2710 DATA3242, 17, 33, 69, 137, 17, 49, 81 ,145,254,2,2,254,2,2,254,4,17

2712 DATA1 7, 17, 17, 17, 17, 17, 0,68, 36, 16, 36, 68, 130, 0,0

2720 DATA3240, 2, 5 y 8, 20, 34, 65, 2, 4, 0,0, 128,64, 128, 0,32, 80, 8, 49, 66

2722 DATA0, 0,0, 7, 0,1 36, 68, 40, 16, 32, 192, 0,0

2730 DATA3238, 0,0, 0,0, 0,0, 0,3, 0,0, 0,0, 0,0, 0,0, 7, 15, 15, 7, 0,1 6, 15,0
2732 DATA1 92, 160, 144, 16, 32, 64, 128,0

2740 DATA3236,4,4, 31 ,4,4,7,4,4,32,32,248,32,32,224,32,32
2742 DATA7, 4, 4, 127, 2, 4, 24, 0,224, 32, 32, 254, 64, 32, 24,0
2750 DATA3234,0,1 ,1 ,1 ,1 ,31 ,17,17,0,0,0,0,0,240,16,16,17,17,31
2752 DATA 1,1,1,1,0,16,16, 240 , 0 , 0 , 0 , 0 , 0

Program 2. Chinese character output demonstration.

Microcomputing January 1980 33

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I

3

2

4

0

127

0

63

33

63

33

63

4

56

0

32

32

248

32

224

0

252

_Q

248

8

248

8

248

64

56

0

Fig. 2. Chinese character in a 16x16 dot matrix.

used In this program are
decimal, not hex.

Chinese Character Generation
and Output

First, enter the program,
Chinese Character Output
Demonstration (CSAVE name:
CHI32). Make sure there are no
mistakes when you enter the
long data statements, such as
using instead of between
two numbers. Then type RUN
(and RETURN). See Photo 1 for
comparison. It’s obvious that
cramping a Chinese character
into an 8 x 8 dot matrix is not
reasonable, so I used a 16 x 16
dot matrix for each Chinese
character (Fig. 2). Each quarter
of this 16x16 matrix is num-
bered 1,2,3 and 4, starting at the
upper left-hand corner. Each
quarter is further divided into an
8 x 8 dot matrix as the Sorcerer
will do.

If you can understand Pro-
gram 1 (for the omega sign), you
should not have too much
trouble understanding this one.
I put line 150 into the program to
clear the screen first, since I
have not discovered the “screen
clearing” statement for the
Sorcerer yet. (Does anyone
know?) Line 200 is used to limit
the output numbers of the char-
acters to less than 32 for this
demonstration. I tried to put
more characters on the screen,

but have not had any success
yet. The problem is that 32
characters will use up 128 (16 x
8) user-definable graphics keys. I
wonder if the people at Exidy
know a way (in BASIC, please) to
change the data for each key
without wiping out the earlier
graphics data. I tried several ap-
proaches, but if I try to change
the data, then all the characters
on the screen will also change
to identical characters. I end up
with a screen full of the same
characters.

Conclusions

By the way, the translation of
the characters in Photo 1 is:

Chinese Character Output Demonstration
By Timothy Huang

June 10 of the year 68 of the Republic of
China.

The usages of Microcomputers are many,
one of which . . .

Before I try another program
that can handle more char-
acters, I wonder if anyone has
ever encountered the error
message: ? MO ERROR IN XX-
XX. After consulting the list of
Appendix D: Error Messages of
the Sorcerer of “A Short Tour of
BASIC” from Exidy, I cannot
find out what it means.

Well, if anyone who can use
this program would like to share
his or her discoveries about the
special graphics powers of the
Sorcerer, I would appreciate
hearing from you. ■

At Intersystems,
"dump" is an instruction.

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607-25 7-01 90/TWX: 510 255 4346

Using Five-Level Teleprinters

with a TRS-80

Why spend a kilobuck on a fancy printer when surplus 15s and 28s abound. Baudot lives on!

Brian Bateman
PO Box 399
Sharpes FL 32959

U nless you are one of the
lucky ones, you don’t have
a lot of money to spend on a
personal computer system.
Yet, in spite of the groans from
your bank account, and maybe
your wife, you invested in the
Radio Shack “bare essentials”
TRS-80 Level II 16K machine.
After all, who really needs
those extra goodies such as a
line printer, which can cost
more than the computer itself?

Within a couple of months,
you are operating your system
with a fair degree of con-
fidence. It is not until you have
to debug one of your “biggie”
programs or print a biorhythm
chart that you start to ap-
preciate the real worth of hard
copy. Still, it might be difficult
to justify upwards of $1600 fora
printer. But all is not lost, since
I am going to show you how you
can have hard copy for your
machine at a very reasonable
price.

The Radio Shack TRS-80 has
the printer interface in its ex-
pansion interface. It also has

sockets for 32K more memory,
an extra cassette interface, a
real-time clock and a single
chip disk controller. So just to
get the printer interface you
have to buy a box costing $300,
which is definitely a bit much
for the guy who just wants hard
copy. Even without this ex-
pense, the printers themselves
are not inexpensive. Radio
Shack sells one for close to

$1300, which represents a
single expense of more than
the total you have so far in-
vested in the system.

Teletype for Your TRS-80

Fortunately, some of the
older Teletypes are becoming
surplus Items and are being
sold at very reasonable prices.
Probably the most abundant of
these Teletypes are the five-

level Teletype Models 15 and
28.

The Model 15 was last manu-
factured in 1957, and about a
quarter million were produced.
It is a slow machine, typically
60 wpm. This speed, as with all
five-level Teletypes, is the max-
imum speed, i.e., if no shifted
characters are printed, since
the Teletype must waste one
character time in order to per-

LETTERS

FIGURES

9

: C

IIOOO

CR

CR 1

CR 1

01000

5

9 c
10000

blk

blk |

- L
00000

spc

•pc I

... [%_

00100

: c

10100

"C
01 100

: C

III 000

U 8

o

o o o -

CR

CR |

CR L

01000

: c
10000

blk

blk | —

blk 1 +

00000

spc

spc | —
spc 1

00100

Uo

o

XXX —

N

= c
01100

M

S

IIIOi

c

0

p

5/8 |

1 1 001

$

$ c

OIOOI

"(♦)

: c
10001

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00001

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6

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01 1 01

t c

1110 1

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001 10

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101 10

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1 1010

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00110

p

: E
101 10

c

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onto

V

V 1

INK

:

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fig

fig | —
fig [<^

IIOI 1

'(bel)

"C

10010

2

i C

IOOII

: c

000 II

00111

1

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ION 1

u c

Oil 1 1

let

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fig | —
fig L

IIOI 1

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0001 1

u

“ c

001 II

Q

2 1
10-11

:

i

K

‘ c

oil II

let

let |

Mill

7

Communications (alternate char)
Standard

Bell System (TWX)
Stock Market

Weather Code

Baudot 5-Bit Code

special
modified
character
(If any)

NOTE: “fig" * Indicates a shitt to "uppercase"
"let" * indicates a shitt to "lowercase"
"blk" - is interpreted like a null
"spc" -is the space
"bel" - is the bell
"CR" -is the carraige return
"LF" -Is the line feed

LEGEND FOR EACH OF THE ABOVE 64 BLOCKS

Fig. 1. Diagram of the Model 28 type box (viewed from character side).

36 Microcomputing January 1980

form the shift. Although slow, it
gets the job done, producing a
readable hard copy.

The Model 28 (Photo 1) is the
most desirable of the five-level
machines, since it is faster
(typically 75 or 100 wpm),
reasonably quiet and still being
produced, making service and
spare parts plentiful. The only
difference between the 75
wpm and 100 wpm Model 28 is
two gears, which can be ob-
tained from Teletype service
centers.

All of these Teletypes can be
purchased for between $50 and
$200, depending on your re-
sourcefulness and the condi-
tion of the machine. This is a
bargain, since the original price
of these machines was from
$2000 to $3500. The Models 15
and 28 are both heavy-duty ma-
chines capable of 24-hours-a-
day operation.

The primary disadvantage of
the five-level machines is that
they do not have the full ASCII
character set; in fact, they have
only about 54 characters. With
some careful manipulation,
however, you can substitute
these characters for some of
the ASCII characters that it
does not have; after a little
practice you will be able to read
a five-level listing almost as
well as an ASCII listing.

Fig. 1 shows the five-level
character set and how the bits
are arranged for each charac-
ter. Notice that each bit pattern
has two key-codes assigned to
it. This demonstrates that a
particular code is interpreted

differently depending on
whether or not the Teletype is
currently in a shifted or un-
shifted condition. In order to
change this condition, you
must send either a “letters”
(unshift) key-code or a
“figures” (shift) key-code.

Now you can see why that
quoted speed was a maximum
speed. For example, if the Tele-
type is in an unshifted condi-
tion and typing letters, then no
shift would need to be sent, but
if you had to type a number,
then you would have to first
shift then type the number. The
machine would then remain in
the shifted condition until
either the letters code or a
space code was sent.

On most of the five-level
Teletypes, every time a space is
sent theTeletype automatically
unshifts, no matter what its
previous condition was. This Is
a waste of time when you have
to type several numbers with
spaces in between them. The
Teletypes are set up to operate
with or without this feature, but
I suggest that you keep it in
since this puts the machine in a
periodic known unshifted con-
dition. This allows the machine
to synchronize itself with the
computer without the need for
extra wiring and hardware that
would be necessary to allow
the computer to check the sta-
tus of the carriage or type box.

How Five-Level Works

Most of the five-level
machines operate on a current
loop, that is, a closed circuit be-

1

L

START BITS * *

OATA BITS ***** *****

STOP BITS

WORDS PER DATA RATE CHAR /SEC START AND DATA STOP BIT
MINUTE (BAUD) BIT TIMES TIME

60

75

100

45

6.0

22.0ms

31ms

57

7.5

18.0 ms

25ms

75

10.0

13.5 ms

19ms

TYPICAL PROGRAM DELAY COUNTS FOR THE TRS-80

60 words /minute ^ DELI 10 HEX
DEL 2 BB HEX
DEL 3 02 HEX
DEL 4 33 HEX

lOOwords/mlnute : DEL I OA HEX

DEL 2 B8 HEX
DEL 3 02 HEX
DEL 4 22 HEX

Fig. 2. Timing sequence for the letters R and Y.

Photo 1. Teletype KSR Model 28.

tween the power supply and the
selector magnet. Data is trans-
mitted to the Teletype by break-
ing and closing this loop at
carefully timed intervals. Just
about all of these machines
operate with a current of ap-
proximately 60 mA in the loop,
although some of the Model
28s operate with a 20 mA loop.

Fig. 2 shows a typical timing
sequence for the letters R and
Y. Also included is a chart
showing the length of these
times for the different Teletype
speeds. Notice that the start bit
is a break in the current loop,
and after one bit time, the first
bit of the transmitted character
arrives. After precisely five bit
times (six total), the current
loop is forced closed for one
stop bit time. This allows the
machine enough time to set up

for the next character. The
times listed for the stop bit
length are minimums.

Actually, the stop bit length
is unimportant as long as it is
greater than or equal to the
minimum; however, to avoid
slowing the Teletype down too
much, this time should be kept
as close to the minimum time
as possible. The transmission
of alternating Rs and Ys is a
good worst-case test of the
five-level machine, paralleling
the transmission of the As and
5s in an ASCII machine.

When you first get your ma-
chine it will be wise to play with
it a little bit before hooking it up
to your computer. If your Tele-
type has a keyboard, which
most of them have, then you
should hook the keyboard in
series with the printing

C2I+ C20+

Kl

1 1 5 V DC

C2I* C20*

SELECTOR

MAGNETS

n

1.

T

132 A

A

132 A

-W —

C22*

022+

C 9 *

Cl 8* CI27 *

LINE

RELAY

-«

CI28 *

CI7* I0O0A

Fig. 3. Simplified wiring diagram for the Model 28 five-level
Teletype.

Microcomputing January 1980 37

Photo 2. Screw terminal strip (visible behind paper roll with cover
lifted).

mechanism in the current loop
so you can type directly on the
keyboard to the printing
mechanism. In the event that
you have a nonworking key-
board or no keyboard at all,
then you should connect a
switch wired with insulated
alligator clips in series with the
current loop.

Close the switch and turn on
the Teletype, which should
come on and be relatively quiet
with only the hum of the motor.
If, instead, it rattles like crazy,
then the current loop is not
closed. Even though the cur-
rent is small in the loop, the
voltage is 115 volts, so care
should be taken when connec-
ting and using the switch.

Fig. 3 shows the typical cir-
cuits for the Model 15 and 28
five-level Teletype. I have In-
dicated some good points for
completing the 60 mA current
loop. The numbers preceded by
C represent terminal connector
numbers on the screw-type ter-
minal strip (Photo 2) inside the
Teletype. This number when
suffixed with + indicates an
RO or KSR Model 28, and when
suffixed by * indicates an ASR

Model 28.

Keyboard contacts for all
standard Model 28 Teletypes
are terminals C9 and CIO. So to
put the keyboard in series with
the typing unit requires only
that the jumper between C20
and C21 be disconnected and
then two jumpers (C9 to C20
and CIO to C21) be installed.
Terminal CIO is not shown in
Fig. 3 since it is in the keyboard
signal generator loop.

Typically, the keyboard and
typing unit are not connected
together in their normal con-
figuration as they would be In-
stalled by Teletype. However,
even though C9 and CIO would
appear to be in different places,
they are actually adjacent ter-
minal connections on the ter-
minal strip.

To make this a working sys-
tem, the Teletype interface
should be connected to ter-
minals Cl 7 + (Cl 28*), which is
the “ + ” voltage, and
C18 + (C127*), which is the “ - ”
voltage. If your loop current is
much lower then 60 mA and the
Teletype does not print reliably,
you can connect to terminal
C22 + (C22*) instead of

TO FIG. 6

Fig. 4. Teletype interface.

I 3 5 7 9 || 13 15 17 19 21 23 25 27 29 31 3 3 35 37 39

nnnnnnnnnnnnnnrinnn nilj

[UUUUUUUUUUUUUUUUUU

4

6 8 10

12 14 16 18 20 22 24 26 28 30 32 34 36 38

Pin

No.

Signal

Description

1

RAS*

Row address strobe output for 16 pin dynamic RAMs

2

SYSRES*

System reset

3

CAS*

Column address strobe output for 16 pin dynamic RAMs

4

A10

Address line

5

A12

Address line

6

A13

Address line

7

A15

Address line

8

GND

Signal ground

9

All

Address line

10

A14

Address line

11

A8

Address line

12

OUT*

Address line

13

WR*

Address line

14

INTAK*

Interrupt acknowledge output

15

RD*

Memory read strobe output

16

MUX

Multiplexer control output for 16 pin dynamic RAMs

17

A9

Address line

18

D4

Data line

19

IN*

I/O input strobe

20

D7

Data line

21

INT*

Maskable interrupt

22

D1

Data line

23

TEST*

Tri-states the processor

24

D6

Data line

25

A0

Address line

26

D3

Data line

27

A1

Address line

28

D5

Data line

29

GND

Signal ground

30

DO

Data line

31

A4

Address line

32

D2

Data line

33

WAIT*

Processor wait for slow memory

34

A3

Address line

35

A5

Address line

36

A7

Address line

37

GND

Signal ground

38

A6

Address line

39

GND

Signal ground

40

A2

Address line

Fig. 5. Expansion port edge card (viewed from rear of TRS-80) and
pin-out designations.

C18 + (C127*), which bypasses
a resistor, thus increasing
the loop current. There is a
jumper between C9* and C127*
as shown, so C9* can be used
instead of C127* if it is more
convenient.

The Model 15 is extremely
simple with respect to its wir-
ing. It has a two conductor wire,
which is connected to the
selector magnets on one end
and a one-quarter inch phone
plug on the other end. The
keyboard is connected to
another one-quarter inch phone
plug the same way. If the
Teletype does not come with a
power supply, then you must
build a 120 mA, 115 volt dc
power supply with about a 6000
Ohm, 25 Watt resistor in line to
control the loop current, which
should be adjusted to 60 mA.
The selector magnets, the key-
board, the Teletype interface

and the power supply should all
be connected in series with
each other to form the working
system.

Once you have finally closed
the loop, type on the keyboard
if you have hooked it up, or
open and close the switch rap-
idly and the Teletype should re-
spond by typing some charac-
ters. At this point, it doesn’t
matter what it types, just so it
types. If it passes this test, you
can feel reasonably confident
that the computer will be able
to “talk” to it.

Basically, the computer has
to “make and break” the circuit
in precise patterns to instruct
the Teletype as to what char-
acter to print. To do this we
need some kind of switch.
Since I don’t like any more
mechanical things in the sys-
tem than I have to have, I chose
a high voltage transistor. It

38 Microcomputing January 1980

74LSI0 T I4-Vcc CSV)
74LS04; 7-GND

74LSI75 I6-V C c(5V)
8 -GND

T I -Tronsformer, Radio Shack 273-1384
R I -Bridge Rectifier, Rodio Shock 276-1151
Cl -IOOO m F, 16V Capacitor, Rodio Shack 272-1008
C2 -lOO^F 16V Capacitor, Radio Shock 272-1005
RGI -7805 Voltage Regulator, Radio Shack 276-1770

Fig. 7. 5 volt power supply circuit.

TO. Fia 4

Fig. 6. Computer interface.

doesn’t have to handle much
current, but it should have a
voltage rating of at least 150
volts. Fig. 4 shows this inter-
face. It should be located rela-
tively close to the Teletype.
This interface actually does the
switching of the 60 mA current
loop.

Now, we need to have some-
thing to switch the transistor
on and off.

The Computer Interface

On the back of the TRS-80
keyboard unit and the screen
printer port on the expansion
interface, there is a 40-pin bus
with 20 tabs on each side of the
printed circuit board. The pin-
out designations are shown in
Fig. 5.

The Z-80 microprocessor
allows for 256 non-memory-
mapped I/O devices to be con-
nected to it. To “talk” to a
device the Z-80 must place its
“device address” (port ad-
dress) on the lower eight ad-
dress lines (Aq-A 7 ) and at the
same time pulse the I/O sync
line (OUT*).

Fig. 6 shows the schematic
for the computer interface. If
you follow the logic of the
diagram you will see that it is
configured for device address
3A (hex) or 58 (decimal). You
can see that the diagram is ex-
tremely simple and only re-
quires three chips. I used LS
low-power Schottky chips for
low power; however, regular
TTL chips would work just as
well. This circuit requires a
minimal 5 volt power supply
(see Fig. 7).

Once you have built this cir-

cuit, which should be located
near the computer, just con-
nect a pair of wires between the
two interfaces. Also connect a
40-conductor ribbon cable with
connector appropriately to the
computer interface as shown.
One note of caution here could
save your having to rewire the
ribbon cable! It seems that
Radio Shack has labeled their
40-pin bus upside down. In
other words, pin 1 is really pin 2
and pin 2 is really pin 1 on a
standard connector and so on.
Once you have triple-checked
your wiring, you are ready to
hook it all together.

One preliminary check you
can make on the interface is to
turn on the Teletype and type in
the BASIC command “OUT
58,15.” This should cause the
Teletype to go quiet, except for
the motor hum (i.e., close the
loop). If it does not, then you
have a problem somewhere. If
this works OK, then issue the
command “OUT 58,0.” This
should cause the Teletype to
rattle. Again, issue the com-
mand “OUT 58,15.” If the
Teletype again goes quiet, then
you have a working system.

Software

Listing 1 shows the five-level
driver routine. In some places it
is seemingly clumsy, but I
wanted to make the code posi-
tionally independent. In other
words, without the use of an
assembler, you can move this
code around in memory,
change two bytes (7F66 and
7F67) to the beginning address
of the lookup table, and it will
run. This was an extremely
useful feature in the early days
when I didn’t have an assembler
and even after I did finally get
one. The entire driver subroutine
is composed of less than 256
bytes of code.

The first 5F (hex) bytes of
code are the ASCII-to-five-level
lookup table. The relative loca-
tion in the lookup table, with
zero as the beginning, repre-
sents the ASCII character that
it is equivalent to. For example,
relative location 41 (hex) has
the five-level equivalent for the
letter A stored there. There are
different types of information
about the letter stored at that
location, and each of the eight
bits has its specific meaning
(see Fig. 8).

Now that the lookup table has
been established, we have
to break this information down
and send it to the Teletype.
Relative byte 60 (hex) is the
location I reserved to store the
condition of the carriage, that

is, shifted or unshifted. This
brings us to the entry point of
the code, relative byte 61 (hex),
which is labeled ENTRY. The
code basically stores the ASCII
character within the index in-
struction located at the label
CHAR and then checks to see if
the character is a legal charac-
ter (i.e., less than or equal to 5F
(hex)). This check is done by add-
ing AO (hex) to the ASCII
character and checking for
overflow. At label CHAR, the
five-level equivalent for the
ASCII character to be printed is
loaded into the accumulator.
The labels SPCK, LFCK and
CRCK check for special cases
(i.e., space, line feed and car-
riage return), since a carriage
condition check is not neces-
sary for these characters. In
fact, the space, as I mentioned
before, also unshifts the car-
riage regardless of its previous
state.

The label PRTCHR checks bit
7 of the five-level character to
see if the character requires
that the carriage be in the
shifted or unshifted condition
prior to printing the character.
It then dispatches it ap-
propriately to be set up for out-
put to the Teletype.

In the location SHIFT, the
shift status is stored in bit 0,
and bit 7 being set signifies
that two characters need to be
output before returning to the

Listing 1. Five-level TTY Driver routine.

1000
i§ m
1121
1131
1141

LISTING 1

BAUDOT TTY DRIVER *****

IT EXPECTS CHARACTER TO BE IN REG I ST ER "A"

003A

11050 PORT

EQU

3AH

fllA

01061 DEL 1

EQU

0AH

00B 8

0 10 70 0EL2

EQU

08 8H

0002

0 1080 OEL 3

EQU

2

0022

01091 OEL 4

t QU

22H

01100 ;

7F00

0 1110

ORG

7F0 0H

7F0 0 4 0

0 1120 ORIGIN

OEFB

4 0H

7F0 1 4 0

01130

0 EFB

4 0H

Microcomputing January 1980 39

7FI2 40

0 1140

UtFB

40H

7F74 0 5

02190

PUSH

OE

7F03 4 0

01150

DEFB

40H

7F 75 E5

02200

PUSH

HL

7F 0 4 4 0

0 1160

DEFB

4 0H

7F76 DO 7E00

02210 CHAR

LO

A » (1 X+ 0 )

7F0 5 4 0

0 1170

0EF6

4 0H

7F79 11FEF6

02220

LO

OE,0F6FEH

7F 0 6 40

01180

DEFB

40H

7F7C 0E3A

02230

LO

CfPORT

7F 0 7 CA

01190

DEFB

0CAH

7F7E FE48

02240 SPCK

CP

4 6H

7F 0 8 4 0

01200

DEFB

4 0H

7F 80 2006

02250

JR

NZ ,LFCK

7 F 99 40

01210

OEFB

40H

7F82 00 CB 60 86

02260

RES

0,(1 X+SHIFT -OR IGIN)

7F IA 44

01220

OEFB

44H

7F 86 182A

02270

JR

0 UT CHR

7F08 40

01230

OEFB

40H

7F88 FE 44

02280 LFCK

CP

4 4H

7F0C 40

0 1240

OEFB

40H

7F8A 2 826

02290

JR

Z ,0 UT CHR

7F0O 5 0

01250

OEFB

5 0H

7F8C FE5 0

0230 0 CRCK

CP

5 0H

7F0E 4 0

0 1260

OEFB

4 0H

7F8E 200 7

02310

JR •

NZ , PRTCHR

7F0F 4 0

0 1270

OEFB

40H

7F90 3E44

02320

LO

A * 44H

7F10 40

0 1280

OEFB

4 0H

7F92 F5

02330

PUSH

AF

7F 1 1 4 0

01290

OEFB

4 0H

7F93 3E50

02340

LO

A , 5 0H

7F12 4 0

013 0 0

OEFB

40H

7F95 1810

02350

JR

OOUCHR

7F 13 40

01310

OEFB

40H

7F9 7 CB IF

02360 PRTCHR

B IT

If A

7F 14 40

0 1320

OEFB

4 0H

IF 99 2054

02370

JR

NZ ,SB IT

7F15 40

0 1330

OEFB

4 0H

7F9B OOCB 6046

02380

BIT

0,(1 X+SH 1 FT -OR IG IN)

7F 16 4 0

0 1340

OEFB

4 0H

7F9F 2811

0 239 0

JR

Z ,0 UT CHR

7F17 4 0

0 1350

DEFB

40H

7FA 1 DO CB 60 86

02400 UNSHF

RES

0,(lX+SHI FI -ORIGIN)

7F 18 40

i 1360

OEFB

40H

7FA5 F 5

024 10

PUSH

AF

7F 19 4 0

013 70

OEFB

4 0H

7FA6 7B

02420

LO

A »E

7F.1A 4 0

01380

OEFB

4 0H

7FA7 ODCB60FE

02430 OOUCHR

SET

7, (1 X+SHIFT -OR IG 1 N)

7F IB 40

0 1390

OEFB

4 0H

IF AB 1805

02440

JR

0 UT CHR

7F1C 4 0

0 1400

OEFB

4 0H

7F AD 00 CB 6 06 E

02450 NEXT

RES

7, (1 X+SHIFT -OR IG IN)

7F ID 40

01410

DEFB

40H

1FB 1 FI

02460

POP

AF

7F1E 4 0

01420

OEFB

4 0H

7FB2 2E07

0 24 70 OUTCHR

LO

L#7

7F IF 4 0

0 1430

OEFB

4 0H

7FB4 0F

02480 LOOP

RR CA

7F20 48

0 1440

DEFB

48H

7FB5 30 10

02490

JR

NC, SPACE

7F21 DA

01450

DEFB

00 AH

7FB 7 2 6 FF

02500 MARK

LO

H,0FFH

7F22 £2

0 1460

OEFB

0E2H

7FB9 E061

025 10

OUT

(C),H

7F23 E2

0 1470

OEFB

0E2H

7FBB 060A

02520

LO

B ,DEL 1

7F24 02

01480

OEFB

00 2H

7FB0 C5

02530 T IM 1

PUSH

B C

7 F25 40

0 1490

OEFB

40H

7FBE 068 8

02540

LO

B ,0EL2

7F26 F 4

01500

OEFB

0F4H

7FC0 10FE

02550 OL 1

OJNZ

OL 1

IF 21 0 6

01510

OEFB

00 6H

IF C2 Cl

02560

POP

8 C

7F28 D £

01520

OEFB

00 EH

IF C3 10F 8

02570

OJNZ

T IM 1

7F2 9 £4

0 1530

OEFB

0E4H

7FC5 180E

02580

JR

ENB IT

7F2A 0 6

0 1540

OEFB

00 6H

7FC7 2600

02590 SPACE

LO

H » 0

7F2B F 4

01550

OEFB

• F4H

7FC9 E061

02600

OUT

(C) ,H

7F2C 0 8

0 1560

OEFB

00 8H

7FCB 060A

02610

LO

B .DEL 1

7F20 C6

01570

OEFB

0C6H

IF CD C5

02620 T IM 2

PUSH

B C

7F2£ F 8

01580

OEFB

0F8H

7FCE 068 8

02630

LO

B ,0 EL 2

7F2F FA

01590

OEFB

0FAH

7FD 0 10FE

02640 OL 2

OJNZ

OL 2

7F30 £ C

0 1600

OEFB

0ECH

7F0 2 Cl

02650

POP

B C

7F3 1 ££

0 1610

DEFB

0EEH

7F0 3 10F 8

02660

OJNZ

T 1 M 2

7F32 £6

0 1620

OEFB

0E6H

7FD5 20

02670 ENBIT

OEC

L

7F33 C2

01630

OEFB

0C2H

7F0 6 2 0DC

02680

JR

NZ ,LOOP

7F34 04

0 1640

OEFB

00 4H

7F0 8 0602

02690

LO

B t DEL3

7F35 £0

01650

OEFB

0E0H

7F0A C5

0270 0 T IM3

PUSH

B C

7F36 £ A

0 1660

OEFB

0EAH

7FD6 0622

0 2710

LO

B ,0 EL 4

7F3 7 CE

0 1670

OEFB

0CEH

7FDD 1 0 f E

02720 OL 3

DJNZ

OL 3

7F38 CC

0 1680

DEFB

0CCH

7F0F Cl

02730

POP

B C

7F39 F 0

0 1690

OEFB

0F0H

7FE0 10F 8

02740

OJNZ

T 1 M 3

7F3A 0C

0 1701

DEFB

00 CH

7FE2 ODCB 60 7E

02750 NCHAR

BIT

7, (1 X+SHIFT -OR IG 1 N)

7F3B FC

01710

OEFB

• FCH

7FE 6 2 0C5

02760

JR

NZ ,N£XT

7F3C 0 £

01720

OEFB

00 E H

7FE 8 El

02770

POP

HL

7F3D OC

0 1730

OEFB

00 CH

IF £9 0 1

02780

POP

OE

7F3E £4

0 174 0

OEFB

0E4H

7FE A Cl

0 2 790

POP

BC

7F3F F 2

01751

OEFB

• F2H

7FE6 FI

02800

POP

AF

7F 4 0 4 0

01760

OEFB

40H

7FEC DOE 1

02810

POP

IX

7F4 1 46

01770

OEFB

4 6H

7FEE C9

02820

RET

7F42 72

01780

DEFB

72H

7FEF DDC8 6046

02830 St) IT

B IT

0,(1 X+SHIFT -OR IGIN)

7F43 5C

01790

OEFB

5CH

7FF 3 2 0BO

02840

JR

NZ ,0 UT CHR

7F44 92

0 1800

DEFB

5 2H

7FF5 OOCB60C6

02850 SET

SET

0,(1 X+SHIFT -OR IGIN)

7F45 42

01810

DEFB

4 2H

7FF9 F5

02860

PUSH

AF

7F46 5A

0 1820

DEFB

5AH

7FFA 7A

02870

LO

A ,0

7F4 7 74

0 1830

OEFB

74H

7F r B 16AA

02880

JR

OOUCHR

7F48 68

0 1840

OEFB

68H

7F61

02690

ENO

ENTR Y

7F49 4 C

01850

OEFB

4CH

00000 TOTAL ERRORS

7F4A 56

01860

UtFB

56H

7F48 5E

01870

OEFB

5EH

SET 7FF5

7F4C 64

01880

OEFB

64H

NCHAR 7FE2

7F4D 78

0 1890

DEFB

78H

0L3 7FU0

7F4£ 58

01900

OEFB

58H

TIM3 7F0 A

7F4F 70

0 1910

DEFB

70H

UL2 7F0 0

7F5 0 6C

01920

OEFB

6CH

T IM2 7FC0

7F51 6E

0 1930

OEFB

6EH

ENBIT 7F0?

7F5 2 54

01941

DEFB

54H

OL 1 7FC0

7F5 3 4A

0 1950

OEFB

4AH

T IM 1 7FBD

7F54 60

01960

OEFB

60H

MARK 7F8 7

7F5 5 4£

01970

OEFB

4EH

SPACE 7FC7

7F5 6 7C

01980

OEFB

7CH

LOOP 7FB 4

7F5 7 66

01990

DEFB

66H

NEXT 7FA0

7F5 8 7A

02000

OEFB

7AH

UNSHF 7F A 1

7F5 9 6A

020 10

OEFB

6AH

SB IT 7FEF

7F5A 62

02020

OEFB

62H

OOUCHR 7F A 7

7F5B OA

02030

OEFB

00 AH

PKTCHR IF 91

7F5C 48

02040

OEFB

4 8H

CRCK 7F8C

7F50 4 8

02050

OEFB

4 8H

OUT CrtH 7FB 2

7F5E 48

02060

DEFB

4 8H

LFCK 7F86

7F5F 48

020 70

OEFB

4 8H

SPCK 7F7E

7F60 00

02080 SHIFT

OEFB

0

START 7F73

7F61 GQE5

• 2090 ENTRY

PUSH

IX

CHAR 7F76

7F63 F 5

02100

PUSH

AF

ENTRY 7F61

7F 64 OO2 100 7F

02110

LO

1 X ,0R 16 1 N

SHIFT 7F60

7F68 00 7778

02120

LO

(IX* CHAR + 2-0R IG 1 N) ,A

ORIGIN 7F 0 0

7F6B C6A0

02130

ADO

A » 0A0H

OEL 4 0022

If 60 3004

02140

JR

NC, start

OEL 3 0002

7F6F FI

02150

POP

AF

OEL 2 0 08 8

7F70 DOE 1

02160

POP

IX

OEL 1 0 00A

IF 12 C9
7F73 C5

02170

02180 START

RET

PUSH

BC

PORT 003A

40 Microcomputing January 1980

MALL

»^S51

TRS-80

ystem PRODUCT S

MALL

■rmas

YSTEM

MACHINE LANGUAGE GAMES

AIR RAID, BARRICADE or RSL-1: - $10.00 each, all 3 for $25.00

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be challenged by other players. Provides hours of fun for you,
and a super program for entertaining friends!

BARRICADE: "8REAK0l)T" for the TRS-80! Break through 5-wall
Barricade with high-speed ball and keyboard controlled paddle!
Trap the ball among the walls and watch it destroy the 100
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RSL-1: Enter graphic patterns with repeating keyboard! Save
patterns on tape (4 furnished). Play LIFE, a game of birth,
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ADVENTURE! $14.95 each, (3 or more, $12.50 each)

Level-II 16K machine language versions of Adventure, the current
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UTILITIES

RSH-2: AN ADVANCED TAPE MONITOR FOR 16K TRS-80' S - $26.95

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THE ELECTRIC PENCIL FOR TRS-80 DISK SYSTEMS - $150.00
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PRINTER CONVERSION PACKAGES - $9.95 EACH

Many programs do not include provisions for printing with either
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following tapes for adding printing functions:

RSM RS-232-C: Adds RS-232-C capability to RSM-2/2D
PENCIL RS-232-C: For cassette version of Electric Pencil
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OTHER TRS-80 PRODUCTS

ESP-1: $29.95 Assembler, Editor & Monitor (8080 mnemonics)
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P. 0. BOX 366

■■ NEWBURY PARK, CA 91320

Reader Service— see page 227

Microcomputing January 1980 41

01000 ;

LISTING 2

01011 ;

01020 ; ****

# BAUDOT HAN0LER ROUTINE *****

0 1030 ;T H 1 S IS A HAN0LER ROUTINE FOR THE BAUDOT TTY

0 1040 ;AN0 IS

TO BE

USED IN CONJUNCTION WITH THE

0 10 50 {BAUDOT

OR IVER

ROUT 1 NE

01060 ;

IT WILL FUNCTION WITH THE TRS-80

0 10 70 ;

LEVEL

ii basic

0 10 80 ;

IF MEMORY IS CHANGED AS FOLLOWS:

01190 ;

4026HC16422) TO 0CAHC202)

01100 ;

4 0 2 7H ( 16423) TO 07EH(126)

n ca

01110

0RG

7ECAH

7F61

01120 BAUDOT

equ

7F61H

7ECA 19

01130 BEGIN

LD

A »C

7EGB 6 7

01140

OR

A

11 CC Ft 00

01150

CP

0BH

7E Cl 2 8#A

01160

UR

Z »L 2

7E0 0 FE 0C

01170

CP

0CH

7ED2 20 16

0 1180

JR

NZ ,L 3

7E0 4 AF

01190

X0R

A

7E0 5 DOB 603

0 1200

OR

( 1 X* 03H )

7E0 8 2810

01210

JR

Z,L3

7EDA OD7E03

0 1220 L 2

LD

A, (IX+03H)

7ED0 009604

01230

SUB

(1 X+04H)

7EE 0 4 7

01240

L0

B, A

7EE 1 3E 0A

0 1250 L 4

L0

A, 0AH

7EE3 C0617F

01260

CALL

Baudot

7EE6 10F9

01270

0JNZ

L 4

7EE 8 1811

0 1280

JR

L 5

7EE A C0 617F

0 1290 L 3

CALL

BAUDOT

7EE0 FE 00

01300

CP

00 H

7EEF 00

01310

RET

NZ

7EF0 003404

01320

INC

(1 X* 0 4H )

7EF3 QO7E04

01330

L0

A, (1 X+04H)

7EF 6 DDBE03

01340

CP

(1 X> 0 3H)

7EF9 79

01350

L0

A t C

7EFA C0

01360

RET

NZ

7EF8 00360400

0 1370 L 5

L0

(1 X+ 0 4H ) v 0

7EFF C9

01380

RET

7ECA

01390

END

BEGIN

00000 TOTAL ERRORS

L5 7EF6

L 4 7EE 1

L3 7EE A

L2 7ED A

BEGIN 7E CA

Baudot 7F6i

Listing 2. Five-level handler routine.

calling program. This situation
occurs when the carriage must
be shifted or unshifted before
the character can be printed, or
whenever a carriage return is
output, since a line feed must
be issued with the carriage
return. This is necessary since
the TRS-80 does not output a
line feed after printing a car-
riage return. It expects the
printer to automatically ex-
ecute a line feed whenever it
sends out a carriage return.

Any jump to DOUCHR in-
dicates that a double character
transmission is about to occur.
The label OUTCHR actually per-

SHIFT BIT

(REQUIRED)

0 * NO SHIFT

1 * SHIFT

forms the transmission of the
character to the Teletype, in-
cluding the bit timing for the
start, data and stop bits. The
label MARK closes the current
loop for one data bit time, and
the label SPACE breaks the cur-
rent loop for one start or data
bit time.

The label ENBIT checks to
see if the stop bit has been
transmitted. If it has then it will
time the stop bit correctly. The
label NCHAR then checks to
see if another character is yet
to be transmitted. The label UN-
SHF issues an unshift (letters)
character, and the label SET

BAUDOT DATA
BITS

issues a shift (figures)
character to the Teletype.

Now that the driver routine is
finished, you are ready to start
talking to the Teletype. At this
point, however, you can only
talk to it through your own
machine-language programs.
To do that you need only load
the accumulator (register A)
with the ASCII character that
you wish to print and then call
this driver routine as a sub-
routine to your program. This is
done with the instruction CALL
7F61H, or CALL ENTRY if you
assemble this driver with your
program.

While this is nice, most
TRS-80 users will probably find
little immediate benefit for this
routine if it can only be used
with their machine-language
programs. Somehow, this driver
needs to be linked to Level II
BASIC and to the TRS-80 Edi-
tor/Assembler 1.1 to be a real
benefit.

Let’s take the case of Level II
BASIC first. When the TRS-80 is

powered up, it automatically in-
itializes itself to communicate
with the TRS-80 line printer
through the expansion inter-
face. Now we need to reinitial-
ize the Level II pointers to our
routine rather than its own.
This pointer is located in the
Lineprinter Control Block at
decimal address locations
16422 and 16423. We cannot
just put the entry address of the
driver routine here, since there
are certain things we have to
handle other than just print out
the character itself. The TRS-80
line-printer routine takes care
of functions such as counting
the number of lines printed, and
if it receives the result of the
command LPRINT CHR$(12), it
can even skip to the top of a
new page. Since I was going to
the trouble of writing the driver,
it seemed only reasonable that
I should also include these fea-
tures.

Listing 2 shows the software
interface between Level II
BASIC and the driver routine. In
actuality, this routine will be
combined with Listing 1 and
assembled together. In this
situation, Listing 1 appends to
Listing 2 to form what we might
call the print routine. When an
LPRINT command is encoun-
tered by Level II BASIC, it
breaks up what it is supposed
to print into individual
characters and then sends
them to the print routine in
Register-C one character at a
time.

Basically, this routine’s total
purpose in life is to copy the
character from Register-C to
the accumulator Register-A
and then increment the line
counter each time it sees a car-
riage return until the count
equals the lines per page
count. When this occurs, the
line counter is then zeroed out
for the start of the next page.
Both the lines per page count
and the line counter are also
stored in the Lineprinter Con-
trol Block, respectively, at
decimal locations 16424 and
16425.

The only thing left to do now
is modify the pointer address in
decimal locations 16422 and
16423. This pointer requires
two words of memory since it is

BIT NUMBER 7

STOP BIT

(ALWAYS ONE)

START BIT

(ALWAYS ZERO)

Fig. 8. Eight-bit configuration.

42 Microcomputing January 1980

a full 16-bit address and each
word In memory is only eight
bits. The order in which these
locations are loaded is very im-
portant. The Z-80 expects to
see the least significant eight
bits of the address in the first
location and the most signifi-
cant eight bits in the second
location. To find out what we
need to put in these locations
requires some relatively simple
calculations.

Since the entry point to the
handler routine shown in
Listing 2 is address 7ECA (hex),
the first thing to do is break it
up into two parts (most signifi-
cant and least significant). The
most significant eight bits is 7E
(hex) and the least significant
eight bits is CA (hex). Now
unless you are using disk
BASIC, you won’t be able to use
this information directly; you
will have to convert it to
decimal. Converting any two-
digit hex number to decimal re-
quiresthat you multiply the left-
most digit by 16 (assigning
A = 10, B = 11, C = 12, D = 13,
E = 14 and F = 15) and add it to
the right-most digit.

Following this, you will see
that 7 E (hex) is equal to 126
(decimal) and CA (hex) is equal
to 202 (decimal). At this point,
changing the pointers consists
of issuing two Level II BASIC
commands: “POKE(1 6422),
202” and “POKE(1 6423),
126.” Now the LPRINT and
LLIST commands will write
directly to your Teletype as if it
were the TRS-80 line printer.

For those of you who also
want your assembler to list its
output to the Teletype, the solu-
tion is not quite as simple.
Although, with the program
shown in Listing 3, you should
have no problems at all.

This code to modify the
assembler is divided into three
sections. The first section
beginning at the label SETUP
simply takes the other two sec-
tions and overlays them on top
of the assembler in the proper
places. The second section,
beginning at the label START,
should look familiar since it is a
copy of the software interface
between Level II BASIC and the
driver routine. This routine is
also needed with the assembler

to make it perform its printer
functions properly.

The third section, consisting
of the code associated with
labels MEM1 and SETMEM, is
mainly a nondestructive memo-
ry size routine. It will go
through memory looking for the

last location of RAM. Once it
finds that, it will subtract the
amount of memory taken up by
the print routine and then pass
that result to the assembler at
its memory size. This is
necessary since the assembler
goes all the way to the end of

memory to store its symbol
table.

To make the patch to the as-
sembler and then run it, reset
the machine and answer the
memory size query with a num-
ber that will protect your print
routine when you load it. In a

0 1000

i

010 13

i

01020

; THIS

PROGRAM

WILL MODIFY THE TRS-80 ASSEMBLER

01030

; SO THAT AN ALTERNATE PRINT ROUTINE

01040

; CAN 6t USE0 .

THE ENTRY P0 1 NT OF THE

0 13b 0

| PRINT

ROUT INE

SHOULD BE EQUATED TO "BAU00T".

0 1060

; "SIZE

" SHQULO

BE EQUATED TO THE SIZE OF THE

01070

; PR 1 NT

ROUT 1 NE

IN BYTES PLUS 20 EXTRA BYTES.

0 1080

; THIS

ASSUMES

THAT THE PRINT ROUTINE IS LOCATED

0 1090

| AT THE END OF

MEM0R Y.

01100

5

01110

; YOU MUST LOAD

BUT NOT EXECUTE BOTH THE ASSEMBLER

01120

; AND THE PRINT

ROUTINE BEFORE LOADING AND EXECUTING

0 1130

; THIS

PROGRAM.

0 1140

*

0 1 1b 0

{PROGRAM NAME -

- "ASMM0D"

0 1160

t

7E 00

01170

0RG

7E0 0H

FFb 5

01180

8 AU00T

equ

0FFbbH

0130

01190

SIZE

EQU

130H

7E 00

2 119 7E

01200

SETUP

L0

HL .START

7E03

1 1AA4b

01210

L0

DE , 4bAAH

7E06

014100

0 1220

L0

B C, SETMEM -ST ART

7E09

EDB 0

0 1230

L0 IR

7E 06

2 IbA 7£

0 124 0

L0

HL .SETMEM

7E0E

1 19b46

0 12b 0

L0

QE,469bH

7E11

010A 00

01260

L0

B C.0AH

7E 14

EO80

01270

LD IR

7E16

C38A46

01280

JP

468AH

7E 19

79

0 1290

START

L0

A » C

7E 1A

B 7

0 1300

OR

A

7E 18

FE 08

01310

CP

06 H

7E ID

280A

0 1320

JR

l ,L2

7E IF

FE0C

01330

CP

0CH

7E2 1

2 016

0 1340

JR

NZ ,L 3

7E2 3

AF

0 13b0

X0R

A

7E24

DOB 6 03

01360

OR

(1 X+03H)

7E2 7

2810

013 70

JR

Z.L3

7E29

00 7£ 03

0 1380

L2

LD

A, <1 X+03H)

7E2C

00 9604

01390

SUB

(IX+04H)

7E2F

47

01400

LD

B .A

7E30

3E0A

01410

L 4

L0

A.0AH

7E32

CO 5 bFF

01420

CALL

BAUDOT

7E3b

10F9

0 1430

0JNZ

L 4

7E3 7

1811

0 1440

JR

Lb

7E39

CDbbFF

0 14b 0

L 3

CALL

BAUDOT

7E3C

FE 00

01460

CP

00 H

7E3E

C0

01470

RET

NZ

7E3F

003404

01480

1 NC

UX+04H)

7E42

00 7E04

0 1490

L0

A, (1 X+04H)

7E4b

OOBE03

01b00

CP

(IX+03H)

7E4 8

79

0 1b 1 0

L0

A.C

7E49

C0

0 1^20

RET

NZ

7E4A

00360400

0 1 b 3 0

Lb

LU

(IX+04H) ,0

7E4E

C9

0 154 0

RET

01bb0

5

7E4F

23

01b60

MEM 1

1 NC

HL

7Eb 0

7L

0 1b 70

L0

A , (HL )

7Eb 1

47

01b80

L0

b.a

7Eb 2

2F

0 1b9 0

CPL

7Eb 3

77

0 1600

L0

(HL ) ,A

7E5 4

BE

0 1610

CP

(HL)

7Ebb

70

01620

L0

(HL ) .B

7E5 6

28F7

01630

JR

Z .MEM 1

7Eb 8

AF

0 1640

X0R

A

7Eb 9

C9

0 1 6b 0

RET

7EbA

COE 04b

01660

SETMEM

CALL

4bA AH+MEM 1-START

7EbD

Cb

0 16 70

PUSH

BC

7Eb£

013001

0 1680

LD

BC.SIZE

7E61

ED 42

01690

SBC

HL ,BC

7E63

Cl

01700

POP

BC

7E00

01710

EN0

SETUP

00000 TOTAL ERRORS

MEM 1 7E4F

Lb 7E4A

L 4 7E 3 0

L 3 7E39

L2 7E29

SETMEM 7EbA

START 7E 19

SETUP 7E0 0

SIZE 0130

BAU00T FFbb

Listing 3. Assembler modification.

Microcomputing January 1980 43

Microcomputing January 19W

t

FEF 8 48

0 16 70

OEFB

4 8 H

{ EOT

FEF9 48

01680

DEFB

4 8 H

{ ENG

FEFA 48

01690

DEFB

4 8 H

{ ACK

FEFB 48

0 1700

DEFB

4 8 H

{ BELL

Listino 4. Special handler routine.

FEFC 48

01710

DEFB

48H

{ BS

FEFO 4 0

0 1720

DEFB

4 8 H

1 HT

FE FE 44

01730

DEFB

4 4H

{LINE FEED

FEFF 48

0 1740

OEFB

48H

J VT

01000

i

LISTING 4

FF 00 48

0 1750

OEFB

48H

J FF

01010

i

FF 01 50

01760

DEFB

50H

{ CARRIAGE RET

0 1020

9

* bAUDOT HANDLER ROUTINE *****

FF 02 48

01770

OEFB

48H

; SO

01030

JTHIS IS A HANDLER ROUTINE FOR THE BAUDOT TTY

FF 03 48

0 1780

DEFB

4 8 H

; SI

01040

;ano is

TO BE

USEO IN CONJUNCTION WITH THE

FF 04 48

0 179 0

DEFB

48H

{ OLE

0 103 0

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SOFTWARE

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• PRESS 'M' TO RETURN TO MENU «-«-

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ALIEN INVASION 9.95

AMPERSORT II 15.95

APPLE ALLEY 6.95

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BATTLEFIELD 9.95

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DATABASE MAILER 29.95

DEATH RACE 15.95

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SIRIUS

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46 Microcomputing January 1980

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characters that I wanted.

I started with the easiest
ones first. The bell was the first
to go. On one of my Model 28s,
the bell code was tied to the
spacing mechanism, which
meant that after the character
was decoded the carriage would
also advance one space. That
meant that no extra care would
be needed here: however, my
other Model 28 did not space
after this code, which meant
that after I printed my character
in this slot I would have to im-
mediately print a space also
just to advance the carriage.

Typically, none of these
special cases, excepting, of
course, the space itself, will
automatically advance the car-
riage after printing the charac-
ter. You will have to check your
individual machine to see if it
spaces or not and adjust the
program accordingly. If you
really know the Model 28, there
is a way you can tie these char-
acter decodes to the spacing
mechanism, but this is certain-
ly not a necessity, since it can
easily be programmed around
as I will show you.

I also used both upper and

lowercase blanks and perhaps
the little more obscure upper-
case space. Even though the
uppercase space did, in fact,
space after printing, it had the
other side effect of auto-
matically unshifting the car-
riage after printing, which also
had to be programmed around.

The only really clever one
was the use of the letters and
figures codes themselves. If
the carriage is in an unshifted
position and the letters code is
issued, it is essentially a NOP.
This is also true if the figures
code is issued and if the car-
riage is already in a shifted con-
dition.

This would be a necessity if
an operator had to type on the
Teletype keyboard, since one
slip-up would print an un-
wanted character. However, I
considered my TRS-80 to be a
nearly perfect typist and would
know the condition of the car-
riage at all times. So I decided
that if the carriage was current-
ly unshifted and a letter code
was issued, this would mean a
character should be printed. If
the carriage was in the un-
shifted condition and a figures

code was issued, then I would
take that to mean that indeed a
shift was intended and as such,
only a shift would be done.

A similar discussion would
follow in the case of the car-
riage being in the shifted condi-
tion. Of course these, like the
other special codes, did not
come with an automatic space,
so a space must be output after
the use of one of these codes to
print a character.

After all this work, which was
easier than it appeared on the

surface, I was able to add six
more characters to the basic
set. In fact, if you were willing to
modify the Teletype mechani-
cally, you could disconnect the
function levers from the upper-
case carriage return and line
feed. This would add two more
characters to the character set
and bring you up to the theoreti-
cal maximum character set for
the five-level machine. This
would then allow you to print the
complete Level II BASIC useful
character set.

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Microcomputing January 1980 47

MAKE YOUR

TRS-80

A 3-SPEED

This simple addition allows either normal operation, a 50% increase, or a 50%
decrease in CPU speed. Unlike other speed mods, this one may be changed AT ANY
TIME without interrupting program execution. This is critical in machine language
programs where there's no software access. Shortens calculations, sorts, and
CLOAD and CSAVE times. The low speed simplifies de-bugging, slows a Level II
LIST, and ELIMINATES KEY-BOUNCE without software overhead. Fits inside the
keyboard unit with only 4 easily accessible connections, and is easily removed if the
computer ever needs service. The Mumford Micro 3-speed kit has been field proven
by its many users and complete satisfaction is guaranteed. Kit includes all parts and
clearly illustrated instructions for $24.95. Fully assembled and tested $29.95

DUPLICATE SYSTEM TAPES WITH “CLONE”

This machine language program makes duplicate copies of ANY tape written for
Level II. They may be SYSTEM tapes (continuous or not) or data lists. It is not
necessary to know the file name or where it loads in memory, and there is no chance
of system co-residency. The file name, entry point, and every byte (in ASCI I format)
are displayed on the video screen. Data may be modified before copy is produced.
CLONE $16.95

RAM TEST FOR LEVEL II

This machine language program tests memory chips for open or shorted address or
data line§ as well as intermittents. It tests each BIT for validity and each BYTE in the
execution of an actual instruction as in real program execution. Bad addresses are
displayed along with the bad data and proper data. One complete test of 48K takes
just 14 seconds. Also includes a test for errors induced by power line glitches from
external equipment. RAMTEST $9.95

PROGRAM INDEX FOR DISK BASIC

Assemble an alphabetized index of your entire program library from disk
directories. Program names and free space are read automatically (need not be
typed in) and may be alphabetized by disk or program . The list may also be searched
for any disk, program, or extension; disks or programs added or deleted; and the
whole list or any part sent to the printer. Finally, the list itself may be stored on disk
for future access and update. One drive and 32K required. INDEX $19.95

EDIT BASIC PROGRAMS WITH ELECTRIC PENCIL

This program allows disk users to load Basic programs into the disk version of
Electric Pencil for editing. Now you can edit line numbers, move program segments,
and search for the occurance of any group of characters. PENPATCH $9.95

INCLUDE 75C POSTAGE— CALIFORNIA RESIDENTS ADD 6% SALES TAX

MUMFORD MICRO SYSTEMS

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Another Business Solution From:

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I have not modified my Tele-
type yet, so I can only choose six
characters (out of my desired
eight) to add to my character
set. Of the eight characters that
I previously mentioned were
missing, I chose to leave out the
@ and t. In place of the @, I de-
cided to just output a space, and
in place of the t, I used !. If you
wanted to be a bit tricky, you
could have the driver routine
print the letters AT each time it
was supposed to print an @.
These extra type keys (called
pallets— see Photo 6) can be ob-
tained from the Teletype service
center for about 50 cents
apiece.

The modification of the type
box is very easy. The type box is
held in place by a clip to the
right-hand side of the type box
as shown in Photo 3. Once the
type box has been removed
from the Teletype, remove the
two bolts on either side of the
type box (Photo 4) and remove
the back cover (Photo 5). In
Photo 6, you will see the hooked
end of the spring that is nor-
mally inserted into the slot on
the pallet as is pointed out in
Photo 5. To install a new pallet,
insert the pallet with no spring
attached into the appropriate
hole as shown in Photo 4, then
slide the spring over the pallet
and push the hooked part of the
spring through the hole in the
pallet as shown in Photos 5 and
6. Reassemble the type box to
complete the modification.

Now that you have seen how
I modified the Model 28 type
box and how it will work, let’s
take a brief look at Listing 4 to
see how the software has to
handle it. Again, the first part of
the program should be familiar
since it is another copy of the
handler routine. The label
ORIGIN again defines the be-
ginning of the lookup table,
which has been a little better
documented in order to help
you change the character
translation easily. In the first
routine, I used blanks (40 hex)
as the translation for illegal
characters. However, in this
routine, I cannot do that since I
have made the blank a printable
character. So for the illegal
characters, I just output a lower-
case space, which now is the

only character that for sure will
not print any character on the
paper.

For the most part, the labels
in this routine have similar
meanings to the labels in the
first driver routine. The label
PRCENT signifies the begin-
ning of special character
checking. A jump to the SPACIT
label will print the character
and then output a space. This is
used after a character that
does not automatically ad-
vance the carriage is printed.
The label ASTER is the check
for an asterisk. It is a good ex-
ample of this need since it is
the unshifted letters code,
which does not automatically
advance the carriage after
printing. You can see that as
soon as the asterisk is detected
a jump is made to the SPACIT
label.

This example gives you the
tools you need to use any char-
acter decode that does not au-
tomatically advance the car-
riage by adding a similar check
for that character into the code.
A good place to add any addi-
tional checks that you might
need would be immediately be-
fore the ASTER label. For in-
stance, on my Model 28, the up-
percase blank (now a >) and the
bell both advanced the carriage
automatically so I didn’t need to
do any checking for them. How-
ever, it is possible that your
Teletype may not advance the
carriage automatically. In that
case, you would need to add two
checks for these decodes im-
mediately before the ASTER
label.

Although the first driver
routine was relocatable any-
where in memory, this one is
not. In order to move this one
around, you must assemble it
at the desired location.

After you understand how the
program works, you can
logically extend this knowledge
to develop an even simpler pro-
gram to communicate with
other Teletype machines (e.g.,
the ASR-33 Teletype). Most of
the other Teletypes are ASCII,
which means that no lookup
table is required, and which
additionally means that no shift-
ing is required to print any of the
characters. ■

48 Microcomputing January 1980

Great News from HMCT

TRS-80* MODEL I AND MODEL II IN STOCK

Before you purchase your TRS-80* Model I and
Model II from your local Radio Shack, or consider
Mail order for a discount, let me offer you an alter-
nate choice. Houston Micro Computer Technolo-
gies, Inc. has been providing TRS-80 Software and
Hardware to hundreds of users for almost 2 years.
We are not a mass merchandiser nor are we a dis-
count house, but a group of professionals dedicated
to helping businesses implement microcomputers to
their greatest advantage. Here are just a few of the
advantages we offer over Radio Shack.

DELIVERY

RELIABILITY

SATISFACTION

VALUE

SERVICE

Less than 30 days**

Each unit 100% tested
prior to delivery
Sold by computer profes-
sionals who understand
what you need your com-
puter to do

Trade in value on Model I
systems dependent upon
condition and
configuration
National service on all
products we sell includ-
ing TRS-80s*

CONFIGURATION As a distributor for many
lines of computer
peripherals we can tailor
your system to your exact
hardware requirements
SOFTWARE We are an already estab-

lished Model I Systems
House with an extensive
software library

Maybe you believe a mass merchandising organi-
zation or a discount operation is who you should
trust your computer hardware selection to. Person-
ally we like to think you would prefer to deal with
specialists and professionals who will spend the
time with you personally or on the phone to assist
you in your choice of equipment based on your
needs and specifications.

All equipment purchased from Houston Micro Com-
puter Technologies, Inc. is fully warranted and
backed by national service organizations including
Radio Shack.

For further information call collect, 713 / 661-2005 or
write.

'* Delivery of Model II subject to availability.

‘TRS-80 Is a registered trademark of the Tandy Corporation.

Texas residents add 6% sales tax • MasterCharge • Visa

HOUSTON MICRO COMPUTER TECHNOLOGIES, INC.

Home and Business Computer Specialists

5313 BISSONNET • BELLAIRE • TEXAS • 77401 • 713/661-2005

A Video Board
from Ithaca Intersystems

Good luck with Ithaca’s memory kits prompted this author to choose an 1 1 memory board.

Ernie Brooner
Box 236

Lakeside MT 59922

W hen putting together my
first micro, I was greatly
confused by the available I/O
choices. I remember wondering,
for example, why some termi-
nals were self-contained, while
others used separate key-
boards and video boards and
why some were serial and
others parallel.

Being familiar with Teletype
practices, I finally chose what
is commonly referred to as a
“glass Teletype,” or, more im-
politely, a “dumb terminal.” In-
terfacing this device required
plugging a separate I/O board
into the S-100 bus. I soon
learned that computer I/O can
be frightening in any form,
largely because I chose the Im-
sai MIO with its now infamous
documentation. In retrospect,
however, I have to admit that it
has good hardware.

Although serving well for
business use, such an arrange-
ment does not fully exploit the
available technology for such
uses as graphics and text-pro-

cessing; hence, sooner or later, I
felt it necessary to go the route
of completely separate video
processing, via a board internal
to the micro itself and some
slightly sophisticated software
to permit on-screen editing,
among other features. I had long
wanted lowercase characters,
too, and the 8x10 matrix of
Ithaca’s product even permitted
descenders on those letters
needing tails.

Choosing a Video Board

We hobbyists are sometimes
accused of being frugal. Hav-
ing had good results with
Ithaca Intersystems’ low-priced
memory kits, I chose their video
board largely on the basis of
price.

One of Ithaca Intersystems’
greatest selling points is their
willingness to sell the bare
board and documentation for a
reasonable cost, so that the
builder may use his own surplus
parts to populate the kit or buy
them wherever he feels the deal
is best. This can result in rea-
sonably priced hardware if you
have access to free or inexpen-
sive spare parts. (Ithaca’s video
boards and memory board go
for $25 each, with full documen-
tation.) If you wish, you can also

purchase the fully assembled
video board for $145.

One look at this board indi-
cates that Ithaca Intersystems
is a company whose already
good products have improved
with time. A few years ago their
boards could be described as
good enough for the price; now
the engineering and the board
itself appear to be of the high-
est quality. And after $3000
worth of S-100 components,
with their usually inadequate
and/or erroneous documenta-
tion, this one was a pleasant
surprise.

In addition to clear descrip-
tions of the circuitry and easy-
to-read diagrams, there was a
request for comments and sug-
gestions from the user. Unfor-
tunately, I did have to be a little
bit critical. There were a few er-
rors, such as disparities be-
tween the diagram and parts
lists. Most builders could make
an intelligent guess on these.

Missing was any description
of actually using the board.
And the otherwise outstanding
software furnished used some
labels and some absolute ad-
dresses, posing a slight reas-
sembly problem for anyone not
proficient at such chores.

Evaluating computer com-

ponents is subjective and often
depends on what the buyer is
already using. For example,
some video boards provide a
parallel keyboard port on the
board itself; this one does not.
This is of little importance to
me, since I have a separate key-
board/terminal and I/O board al-
ready incorporated in my sys-
tem, but it could influence the
decision of someone starting
from scratch to assemble a sys-
tem. The point is that any such
system requires data to be in-
put and data to be output.
These are really separate func-
tions, even though they are
often combined for hardware
purposes.

As purchased from Ithaca
Intersystems for $25, the kit
consists of the blank, etched
and labeled board, the assem-
bly instructions, a few debug-
ging suggestions and the nec-
essary software. If you care-
lessly buy good-quality parts,
you might spend another $100
to complete the project. More
realistically, the total cost for
the project, over and above the
initial $25, is $75, which was my
total cost for the board and
everything else I had to pur-
chase.

The kit instructions advise

50 Microcomputing January 1980

the builder to omit heat sinks
on the two 7805 voltage regula-
tors. I used them anyway, but,
with low-power chips, they are
not really necessary. Total
drain from the user’s supply is
between 1/2 and 1 Amp.

Another hardware subject to
note (not just for this, but for
any S-100 project) is the bus
signals actually used or gener-
ated by the new item. Most of
us have run into this sort of
compatibility problem at some
time. This one should be com-
patible with almost anything,
but it does require the read and
write signals, In, Out, Dbin,
clock phase 2 and Sync. It also
must access all address lines,
the data in and data out lines,
both the ± 16 volt supplies and
the 8 volt supply.

The board gets its input from
the bus; the output to your TV
or monitor is via a small coax
cable. This output consists of
the characters plus the horizon-
tal and vertical sync signals. A
worthwhile mod the user can
make is to put a miniature con-
nector at one corner of the
board to facilitate this connec-
tion.

Use of the Board
and Software Driver

For those not familiar with
such projects, the arrangement
consists of IK of memory on
the board, which is addressed
somewhere above the “real”
memory. Ithaca Intersystems in-
dicates this can be located
almost anywhere. Actually,
some software, such as most
versions of Electric Pencil, re-
quire the video display to be at
CC00H, and the driver also as-
sumes this. Such references
must, of course, be changed if
addressed anywhere else.

Software is really the key to
what can be accomplished with
a device like this. Features in-
clude the ability to back up the
cursor and thus erase a mis-
take and control the speed of
the scrolling action. The CPU
and main memory are also com-
municated with so that actions
by either the board system or
the rest of the system will
agree.

This particular board, like
many others, also lets the user

select a white-on-black or
black-on-white display. It also
enables you to use more exotic
software that requires memory-
mapped video. Electric Pencil
is one of the best known of
these.

When first fired up, this
board wants to see a form-feed
(control L) as the first charac-
ter. This is necessary to clear
the screen of the pretty, ran-
dom display of any printable or,
for that matter, unprintable
characters that are in memory.
Unprintables are not X-rated—
they are the ASCII representa-
tion of spaces and carriage re-
turns, for example. Your driver
must supply this initialization
routine.

As is often the case, it also
wants this character, and all
succeeding ones, in the A regis-
ter. Most operating systems
pass this from some other reg-
ister just prior to printing. North
Star likes B, and CP/M likes C. I
am not familiar with any other
specific systems.

In addition to clearing the
screen, the initialization sets
the bounds of the top and bot-
tom line and sets up the scroll-
ing arrangement. After this,
output can be more or less nor-
mally handled, and the video
and CPU will remain on good
terms.

How It Works

Characters are placed in the
appropriate memory cell repre-
senting the particular spot on
the screen where the character
will appear. The cursor can also
be caused to appear anywhere
and occupies the entire rectan-
gle representing that space;
however, there is no conflict be-
tween cursor and character.

If you have selected black let-
ters on a white background, the
cursor block will also be black;
however, the letter that may
happen to be hiding beneath
the cursor is, at that time, re-
versed and appears as a white
letter outlined against the
black cursor. Hence, no display
is ever obliterated by the cur-
sor, even though it is a solid
block.

It happens like this: The char-
acter generator chip is simply a
ROM with the ASCII code for

each character programmed in-
to it; calling any address within
it returns the necessary dot pat-
tern to paint the desired char-
acter on the screen. The ASCII
pattern uses only the lower
bits, and bit seven is reserved
for the cursor; hence, any
screen location can contain, at
the same time, both the cursor
and a character. Needless to
say, the timing among the dot
generator, screen sweep sig-
nals and character is critical.
For this reason, all timing is
derived from an on-board
crystal oscillator.

Most of the needed parts can
be found in computer stores or
radio parts houses. There are a
few exceptions. Two or three of
the chips, such as the charac-
ter generator, are more or less
uncommon. If you cannot lo-
cate one readily, Ithaca Inter-
systems sells them, as well as
the dot generator crystal and
the single resistor pack. (You
can as easily use half a dozen re-
sistors as the pack, but it looks
nicer.) Two other not-so-com-
mon items are the trimpots
used to adjust the centering of
the video display on the moni-
tor.

The hardware is fairly simple
in view of the construction
notes provided with the kit.
Checkout is feasible with
nothing more than a VOM and a
logic probe, unless there are se-
rious timing problems, in which
case you send it back to Ithaca
for help. My recommendation is
to add it to the existing system,
if there is one, without attempt-
ing to actually use it.

It should be possible, if it is
all there, to use your FILL or
POKE commands, depending
on your version of BASIC (or
even panel switches) to place
ASCII characters in the mem-
ory cells within the bounds of
the video board (i.e., 52 to 53K,
if that is where you put it). They
should then display on the
screen. If not, some trouble-
shooting is in order.

If this can be accomplished,
there is nothing left to do but
write the software. Not mean-
ing to frighten anyone, this is
best done with the help of
someone who has an assem-
bler and/or is familiar with as-

sembly-language programming.
It will actually work right if en-
tered exactly as it is, provided
you are using all the same ad-
dresses.

The software driver furnished
with the kit runs to over 200
bytes. Squeezing it into your
own system might pose a prob-
lem, as there must still be room
for your input and initialization
procedures. North Star, for ex-
ample, allows the user 250
bytes for this purpose. CP/M
has twice that, and other sys-
tems, no doubt, vary.

I chose to relocate my printer
driver as a separate file for use
with North Star. This is not nec-
essary with a larger user area
such as that provided by CP/M.
Some pruning could be done to
save space, but each portion re-
moved could disable some de-
sirable feature.

The attractive thing about
such a system, when installed
intact, is that it permits the con-
tinuous checking for various
control characters that enable
the additional user control and
flexibility.

Summary

This board represents an ex-
cellent buy for people wanting
to include a video display in
their repertoire. Neither the
hardware nor associated soft-
ware is especially difficult, al-
though a beginner would be
well advised to have some ini-
tial help with them. It also helps
to have some other operating
system already in existence, as
an aid to the debugging that
may be needed.

Ithaca Intersystems is ready
to help, as witnessed by their re-
quest for comments and their
offer, in the documentation, to
fix any board that is beyond the
test-equipment capability of
the builder. All video boards are
limited in their display to some
fixed number of lines on the
screen and number of charac-
ters per line (24 by 80 is con-
sidered a nice size). The Ithaca
Intersystems board, along with
many on the market, has 16 lines
by 64 columns. It’s simply a
case of getting what you can af-
ford to pay for. If a 16-line dis-
play is all you really need, by all
means try this one.B

Microcomputing January 1980 51

Route 66 Modem

A modem links your microcomputer to anyplace that has a telephone. Get on the road to

high adventure with this economical design.

Frank J. Derfler, Jr.

PO Box 17283
Montgomery AL 36117

B ack in the innocent(?) early
60s, almost every high-
school-age male in the Middle
West had the “Route 66” fan-
tasy. We dreamed of rolling off
down Route 66 in a fast Cor-
vette in search of romance,
adventure and knowledge.

Well, today we aren’t even
taking any long trips, let alone
fast ones. But we can still ex-
tend ourselves into the world in
search of knowledge, adven-
ture and maybe even romance.
We can extend our computer
selves through the use of a
modem and the regular tele-

phone lines. The price of the
modem I will describe adds up
to $66 if you pay full retail.
Therefore, I call it the Route 66
modem.

Commercial modems are ex-
pensive. When you consider
what they do and the price of
the parts, the typical $200 +
price tag is pretty steep.
Perhaps the gravy in the simple
modems is paying for the R&D
of the exotic high-speed error
detection and correction units,
but I don’t want to pay the tariff
for a simple audio-to-dc con-
verter.

My answer is to send an
order off to a company called
Electronic Systems, which
usually has an ad in the back of
Microcomputing , for a $27.50
modem kit. The modem has a
TTL output, but they also have

an inexpensive TTL/RS-232
board, so it will interface to
most terminals or computers. A
power supply and enclosure
are needed to complete the
package. Access to a frequen-
cy counter and audio oscillator
is almost a must for alignment.

I chose to get the cabinet and
power supply parts from Radio
Shack because they were
handy. If you order from some
of the parts houses advertising
in the back of the magazine,
you may be able to put the
originate-only modem together
for under $50.

Theory

A modem is a communica-
tions device. It takes the output
from your computer or terminal
(usually a ±12 volt signaling
scheme called RS-232) and con-
verts it into audio tones that
can be passed over the phone
lines. Another modem is at the
other end of the phone line.

The second modem converts
the tones back into dc, which it
feeds into its computer or ter-
minal. This means that you can
(theoretically) talk to and ex-
change programs with people
with other brands of systems
than the one you own.

For example, an OSI Chal-
lenger and a TRS-80 may both
be using simliar Microsoft BA-
SIC, but that doesn’t mean they
can swap programs on cas-
settes. The cassette systems
are different. But if they both
use a common RS-232 ASCII
format, they can exchange in-

formation over a telephone or
wireline. It is more complex
than that because they should
have some way to save what
they receive, but there are soft-
ware routines available to do
this already.

Originate and Answer

If the modems at either end
of the line are both pumping out
tones at the same time, then it
becomes obvious that they
can’t both use the same tones,
or they will hear only them-
selves. Four tones are needed
so that the high and low dc
pulses can be converted into
separate high and low tones at
each end.

Several standards exist for
what tones will be used, but the
most common is the Bell 103.
This standard says that the
modem that is on the terminal
end (in a time-sharing system,
for instance) will use 2225 and
2025 Hz for transmit. This is
called the “originate” modem.
The modem on the computer
end of a time-sharing system
(the “answer” modem) trans-
mits at 1270 and 1070 Hz.

Many hobby computer users
have been unpleasantly sur-
prised when they have bought or
built low-priced modems that
were originate only. Two orig-
inate modems cannot talk to
each other. Most kits that adver-
tise “originate or answer”
(including the Electronic Sys-
tems kit used here) must be
hard-wired in either configura-
tion. It is hardly a convenient

The layout of the modem is not critical. The operating controls are
simple. The switch on the panel selects either the answer or
originate modem board.

52 Microcomputing January 1980

The modem board is lower right with the TTL/RS-232 board above it. The power-supply components
are mounted on the board on the left. The two positive voltage regulators are on the chassis wall. The
negative regulator must be insulated from the chassis. The two modem boards are stacked on top of
each other. The modems are grounded through their mounting screws.

way to do it, but by using two of
the kits with a common power
supply and other parts, we can
have both capabilities at a low
price.

The Kits

Electronic Systems will take
credit-card orders when the
phone rates are low. My order
was shipped the next day. Both
kits (shown in the parts list)
were complete with sockets for
the ICs. Construction required
just stuffing the parts into the
holes and soldering.

The 2N2222 transistor sup-
plied with the TTL/RS-232 kit
had a round case without a tab,
so I had to use a VOM to find
out which leads were the emit-
ter/base junction. I felt that this
assumed a sophistication on
the part of the builder which
might not be present. The mo-
dem kit had a properly marked
2N2222. The markings on the
little Mylar capacitors rub off
quickly, so don’t touch theirflat
sides or you will have a pretty
puzzle to work out.

The modem kit came with ex-
cellent documentation that de-
scribed the operation of both
the transmit and receive sides.
Select the proper components
for either originate or answer.
Stuffing and soldering the kit
boards is about a two hour job,
if you take time out to read the
directions.

Phone Line Connection

The modem kit calls for a
high-impedance input such as
a crystal mike and a low-imped-
ance output such as a speaker.
This could be provided in several
ways. First, you could spend a
few dollars for a crystal mike

and a speaker and build them
into a stand that would hold a
telephone handset.

Second, you could buy an au-
dio pick-up such as the one ad-
vertised by the Rondure Com-
pany for $17.50. Third, you
could, as I did, find an old ama-
teur-radio phone patch and use
it to couple into the phone line.
Finally, you could buy two 99
cent transformers and couple
into the phone line that way (as
shown in Fig. 1).

A word of note: If you direct-
couple into the phone line with
a phone patch or the transform-
er system, you will be required
to get the phone company to in-
stall something called a direct
access arrangement (DAA),

which stops unwanted tones
from going down the phone
lines and fouling up the tele-
phone company’s switching
systems.

Interfacing

The output of the modem
board is transistor-transistor
logic (TTL), which is a system of
signaling using + 5 and 0 volts.
Some terminals can use TTL
levels. If you have one of these,
then you don’t need the TTL/
RS-232 board. (See “Parallel Port
to RS-232,” April 1979 Microcom-
puting.)

Electronic Systems also has
a TTL/20 mA current loop board,
so if you are using a terminal
such as a Model 33 you can use
this interface. The majority of
terminals and computers use
an RS-232 interface.

When you make up the con-

necting cable, you must decide
if you are going to plug into a
computer or a terminal. This is
important for several reasons.
First, a computer has a female
RS-232 jack mounted on its
chassis; a terminal has a male.
Second, the standard is set up
so that a computer expects to
receive data (from terminal 5 of
the RS-232 board) on its pin 2
and to transmit data (to termi-
nal 2 on the board) on its pin 3.
A terminal outputs on 2 and re-
ceives on 3 so that it mates with
a computer.

As the modem builder, you
have to decide which device
you need to mate to. If you want
flexibility, then simply prepare
two different cables that plug
into a jack on the modem. In
either case, pins 4 and 5 of the
DB25 plug should be wired to-
gether so the device provides its

Modem kit: Electronic Systems Part No. 109A
TTL/RS-232 Converter: Electronic Systems RS-232

DB25P Plug: Available from Jameco Electronics or with an 8 conductor cable from Elec-
tronic Systems, PO Box 21638, San Jose CA 95151.

Item

Radio Shack Part No.

Neon panel light 272-705

Aluminum cabinet (3.5 x 9 x 6) 272-261

VR1 +5 volt regulator (7805) 276-1770

VR2 + 12 volt regulator (7812) 276-1771

VR3 - 12 volt regulator (7912) NOT LISTED

D1 4 AMP 50 V bridge 276-1146

Cl, C2 2200 uFd capacitor 272-1020

SI SPST switch 275-011

Ac power cord 278-1255

T1 transformer 25.2CT 2 Amp 273-1512

Parts List.

TO MODEM BOARD

6800

( j

t c TO PHONE

f LINE

Fig. 1. This circuit can be used to connect the modem board to the
phone line. T3 and T4 are two identical Radio Shack audio output
transformers (stock no. 273-1380) with their secondaries hooked
together. The capacitors keep any stray dc voltages out of the
transformer.

Microcomputing January 1980 53

The modem tucks in neatly under the monitor. The old phone patch
used to couple into the phone line is on the left.

own clear-to-send signal.

Power Supply

The power supply I’ve shown
(Fig. 2) provides all the voltages
needed with an absolute mini-
mum of parts. The bridge recti-
fier isn’t working as a bridge; it
is working as two separate full-
wave rectifiers in one conve-
nient package— one for +12
and one for -12 volts. The +5
volts is tapped from the +12
volt source. The - 12 volt regu-
lator isn’t a standard item in the
Radio Shack catalog, but many
stores now carry them.

The photographs show the
general layout I used. I just
mounted everything on a piece
of perforated board and used
point-to-point wiring under-
neath. The components run
cool and can handle two
modem boards with no prob-
lem.

Double Talk

If you only use one modem
board, then you will have either
an answer or originate capabili-

ty. If you know exactly who you
are going to talk to, this may be
enough. But to be truly versatile,
you need both capabilities. Al-
though Electronic Systems
gives you the right parts for
either format, there are too
many connections and align-
ments involved for easy switch-
ing.

The best way is to buy two
modem boards, set one up for
answer and one for originate,
connect the audio and power-
supply lines to both in parallel
and switch the TTL input and
output lines between the two
modem boards with a simple
DPDT switch. Doing it is easier
than writing about it, and the
diagram for the switching is
Fig. 3.

Alignment

If you have a friend with a
modem and a lot of patience, it
is possible to align this system
by slowly turning the trimpots
until you are sending and re-
ceiving good copy. The only ad-
justment consists of one pot

VR I

TO "♦S" ON
MODEM BOARD

TO TERMINAL 4
ON RS-232
BOARD

TO TERMINAL 6
ON RS-232
BOARD

Fig. 2. This power supply is simple and effective. The bridge is be-
ing used as two full-wave rectifiers. Note that the pins are different
on the negative regulator and that it must be insulated from the
chassis.

Tone

Logic

TTL Level

RS-232

TTY State

2225 Hz

One

+ 5

-12

Mark

2025 Hz

Zero

0

+ 12

Space

1270 Hz

One

+ 5

-12

Mark

1070 Hz

Zero

0

+ 12

Space

(1270 and 1070 are received by an originate modem)
(2225 and 2025 are received by an answer modem)

Table 1. Tone/level table.

each for the transmit and re-
ceive frequencies. The toler-
ance is about 10 percent or 100
to 200 Hz, so you have to be
close. A frequency counter real-
ly helps. I used a shortwave re-
ceiver with a beat note on the
crystal calibrator for a signal
generator.

These modems are not crys-
tal controlled, so try to set the
unit up under fairly standard
temperature conditions. Some
drifting with age may take
place. The only problems I have
are with some other 300 baud
modems on the end of some
phone lines on some days. It
isn’t consistent. Usually,
switching down to 1 10 baud im-
proves the reliability of com-
munications.

What Do You Say After Hello?

Now that you can get infor-
mation into your machine, what
can you do with it? If you are us-
ing aterminal, you might print it
out on an attached printer. But
many of us want to use our
computers to communicate and
then to manipulate what we re-
ceived.

In the easiest form, you can
stay in BASIC while someone at
the other end talks to you in the
form of line numbers and REM
statements that will keep BA-
SIC from issuing error mes-
sages. You qan then save the
text and programs you received
in your normal way. That is
probably good enough to con-
verse with your friends, but
don’t expect a time-sharing
system to talk to you in REM
statements. You could write a
BASIC program to allow free-
flow discussion, but you would
need a files capability to save
what you got. This is not avail-
able on most cassette systems.

Radio Shack is advertising a
communications software pack-
age for the TRS-80 under cata-

log number 26-1 146. Jim Dvorak
(see “Who Sells Software?”
April 1979 Microcomputing , p.
48) has recently been advertis-
ing a useful program for North
Star users. With a program that
will allow you to talk in plain
text “terminal mode” to a larger
computer and then to save
whatever you receive, you can
literally suck the larger sys-
tems dry of interesting pro-
grams that they will let you list.

One minor operating point:
When your modem is not re-
ceiving a signal, it will sit at rest
in either the logic zero (space)
or the logic one (mark) state
(see Table 1). If it comes to rest
on a logic zero, it will drive your
computer frantic. If you are op-
erating with a time-share sys-
tem as an originate modem,
don’t turn your modem on until
you hear the other system first.
Then act promptly or you might
time out.

If you are serving as an an-
swer modem for someone who
has a commercial originate mo-
dem, you may have to give him
a tone first so that it opens his
transmit line. In this case you
might get some garble until
your modem is in synch. That is
a small price to pay for the ca-
pability to send and receive
computer-to-computer infor-
mation.!

TO TERMINAL 3
ON RS-232 CARD

TO E8 ON ORIGINATE
. MODEM CARD

TO TERMINAL 9
ON RS-232 CARD

Fig. 3. If the you need both an
answer and originate modem, a
simple DPDT switch will allow
you to switch the TTL inputs
and outputs from either modem
board into the TTL/ RS-232
board. The power and audio
leads are hooked to both
boards in parallel.

54 Microcomputing January 1980

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Microcomputing January 1980 55

Thoughts on the
SWTP Computer System

Installment number 8 of this series looks at the new 6809 microprocessor.

Peter A. Stark
PO Box 209
ML Kisco NY 10549

T he king is dead; long live
the king!” So goes an old
saying that may be apropos
right now. ‘‘The 6800 is dead;
long live the 6809!”

Motorola’s 6800 isn’t dead,
of course, but SWTP’s 6800 is.
SWTP has apparently discon-
tinued all manufacture and sale
of their 6800 computer, and is
concentrating completely on
their new 6809-based system. I
say ‘‘apparently” because it is

not entirely certain just how
complete this move is. Will
SWTP continue to support 6800
systems? Will they continue to
sell bare boards or board kits?
Will their disk systems con-
tinue in their present form, or
will they, too, be revamped for
the 6809? Only time will tell.

The only thing certain right
now is that complete SWTP
6800 computers are no longer
available. 6809 systems are
available, but without — as yet
— much supporting software.

As has been evident for some
time, SWTP marketing strategy
has changed over the past year
or two. A 6809 kit will be

available (for $495 with 8K of
memory), but the initial push
is for assembled systems,
mostly with a lot of memory.
SWTP (along with many other
manufacturers) is aiming for
the ‘‘business” market.

In a way, this may be a boon
to SWTP competitors. Espe-
cially in the industrial market,
6800 demand will probably con-
tinue, and now that main-
frames, cards, disk systems
and all the other equipment are
available from other manufac-
turers, that will be all that’s
sold. Unfortunately, none of
these can offer the price/perfor-
mance ratio that SWTP always
has offered.

The Motorola 6809
Microprocessor

The 6809 is like a wolf in
sheep’s clothing. Internally, it
is like a 16-bit processor; exter-
nally, it resembles an 8-bit pro-
cessor such as the 6800. For
this reason, it is hardware-
compatible with older 6800
systems — so that with the ad-
dition of a new CPU board,
older SWTP systems can use
the 6809 — yet it can do soft-
ware tricks not possible before.

It is a vast improvement over
the 6800 in many ways, though
not as compatible with it as
generally thought. (It’s not like
the Z-80 being able to run 8080

programs. 6800 programs must
be modified for new instruc-
tions; a few 6800 instructions
that do not exist in the 6809
must be programmed around.)

The 6809 has two accumula-
tors, but they can be used
together as a 16-bit accumula-
tor. It has two index registers
and two stack pointers. It can
perform 16-bit addition and
subtraction and 8-bit multipli-
cation. It can push and pull
other registers, besides the ac-
cumulators, and has a variety
of addressing modes that can
greatly speed up and shorten
programs. Some of the 6800’s
addressing modes are more
versatile with the 6809 — direct
addressing can be done
throughout memory, not just in
lower memory. Conditional
branches can go anywhere, not
just 128 bytes (more or less) for-
ward or back.

Other addressing modes are
new. For instance, there are in-
direct modes that allow han-
dling data without loading the
index register with a base ad-
dress first. PC-relative address-
ing adds an offset or displace-
ment to the address in the pro-
gram counter, in much the
same way as indexed address-
ing adds an offset to the con-
tents of the index register. This
allows writing completely relo-
catable programs without

The SBC/9 board for the 6809-based computer system. (Photo
courtesy of Percom)

56 Microcomputing January 1980

some of the tricks needed to do
the same on the 6800.

In terms of hardware, the
6809 is available in two ver-
sions: the MC6809 with a built-
in clock oscillator, which re-
quires only an external clock
to set clock speed, and the
MC6809E with external clock
inputs. The MC6809 with the
built-in clock and a 4 MHz
crystal operates at a 1 MHz
clock speed to match older sys-
tems. An 8 MHz crystal (with the
MC68B09 version of the proces-
sor) operates at the higher 2
MHz clock speed; but this is not
compatible with SWTP 16K and
32K memory boards and may
not work with smaller boards
either unless the memory chips
are also replaced. (16K and 32K
memory boards can apparently
not be upgraded to work at the
higher speed, due to the way
the dynamic memory re-
freshing is done.)

SWTP also states in their
6809 CPU board instructions
that the 6800 and 6809 main-
frames may not work reliably
above 1 MHz.

6809 pin signals are a bit dif-
ferent from those of the 6800.
Bus control signals, designed
for allowing other devices to
share the bus with the pro-
cessor, are different. Since the
6809 has a built-in clock oscilla-
tor, there is a clock output
rather than clock inputs. The
clock output is now called the
E, or Enable, signal, instead of
02. This better matches the E in-
puts that the PIA and ACIA
chips have had for years. There
is even a second clock output,
now called the Q output. On the
other hand, VMA (valid memory
address) is now gone.

A third interrupt input, FIRQ
(fast interrupt), has been added
for really fast response. And an
M.RDY (memory ready) input
makes the processor wait for
slow memory. (Shades of S-100
systems!)

When a program is rewritten
to take advantage of the 6809’s
features, it can run a lot faster
than on a 6800. But when it is
just doctored up a little — by
reassembling, for instance —
then it runs somewhat faster,
but not by much ... not enough
to justify the effort, anyway.

(ft

The new SWTP 6809 computer
has a completely redesigned
cabinet, and so looks like
a completely new unit.
Inside, though, there are some
marked similarities.

SWTP 6809 System

The new SWTP 6809 com-
puter has a completely re-
designed cabinet, and so looks
like a completely new unit. In-
side, though, there are some
marked similarities. There’s
still a motherboard with
separate 50-pin connectors for
CPU and memory and 30-pin
connectors for I/O. There’s still
address decoding on the
motherboard and a beefed-up
power supply.

But there are some changes
too. Some, such as the new I/O
addressing on the mother-
board, are minor. Others, such
as the design of the CPU board
and the monitor, are major. In
fact, the CPU board — called
the MP-09 (available for $175 as
a modification to present sys-
tems) — tells the whole story of
the system.

In addition to the 6809, the
MP-09 board has sockets for
memory. But unlike the 6800
CPU boards, the MP-09 does
not use an MC-6830 mask-
programmed ROM monitor and
does not have the 6810 128-byte
scratchpad RAM of the earlier
CPU boards. Instead, it has four
sockets that are for single-
supply 2716-compatible
EPROM, ROM or RAM (like the
MP-A2 CPU board). The new
SWTP 6809 monitor is called
SBUG-E and takes up 2K, or one
socket. That leaves three more.

Those sockets can be used
for 2716 2K x 8 EPROMs; they
can also be used for other pin-
compatible devices. SBUG-E
comes on a mask-programmed
ROM that fits those sockets;

other ROMs may be available
later, or large users may be able
to supply their own. Several
manufacturers have also an-
nounced 2716-compatible
RAMs, which are not yet
available. Thus, the CPU board
has room for up to 8K of
memory in any combination of
ROM, EPROM and RAM.

The four memory sockets are
addressed as follows:

IC1 — E000-E7FF

IC2 — E800-EFFF

IC3 — F000-F7FF

IC4 — F800-FFFF (used for

SBUG-E)

IC4, which is normally used
for the monitor, is always
enabled; the other three
sockets have DIP switches that
allow them to be either enabled
or disabled and determine
whether they are used for ROM
or RAM (by controlling one of
the pin connections).

But here’s the rub. IC1
through IC3 are not usable with
the SBUG-E monitor in a full-
fledged 6809 system, because
I/O in an expanded system will
be moved up into the same
memory region as these
sockets occupy. The extra
three sockets are intended for
dedicated applications (in-
dustrial control, for instance),
where a custom monitor —
other than SBUG-E and one
that would use other addresses
for I/O — would be used. So
these sockets (unlike the 2716
sockets on an MP-A2 6800
board) can generally not be used
for extra software.

The addressing for these
memory sockets is more

thorough than monitor ad-
dressing in older 6800 systems.
Monitor and high memory ad-
dresses are fully decoded, so
that extra addresses are not
used up in vain. This was a big
problem with the 6800 system,
which dated back to days when
memory was so expensive that
nobody ever thought a hobbyist
or small user could afford more
than 32K.

The MP-09 board also has a
14411 baud rate generator; but
whereas 6800 systems only
generated baud rate signals for
110 through 9600 baud, the
MP-09 can generate signals for
as much as 38,400 baud. Since
there are only five baud rate
lines on the motherboard, a DIP
switch and several jumpers are
used on the CPU board to deter-
mine the exact baud rate sig-
nals that exit the CPU board to
the bus. (Read on. In some
cases, this baud rate generator
may have to be disabled.)

Now to the differences. First
of all, the MP-09 has improved
facilities for releasing all buses
during DMA transfers or in
multiprocessor systems. This
is in line with some of the 6809
features, which are designed
for such advanced applica-
tions. This includes the familiar
BA (bus available) line and
some new signals. BS (bus
status) replaces the old 01
signal, and BUS REQ (bus re-
quest) can be strapped on the
110-baud line instead of the
baud rate signal. These two
signals are used to tell other
boards (not yet developed)
what the 6809 is doing.

Since existing boards need a
VMA signal, but the 6809
doesn’t provide it, the MP-09
manufactures a VMA whenever
the 6809 indicates that the bus
is being used and is not
available for other use.

The MP-09 also connects
some of the other new 6809
signals such as BS, clock (Q
and E), M.RDY, BUS REQ and
FIRQ to the 50-pin bus on the
motherboard.

However, the SS-50 bus only
started out with two extra un-
used lines, called UD (user
defined) 1 and 2. Where did all
the new signals go? Back in
1978, there were several

Microcomputing January 1980 57

Pin no. (from

Old SS-50 signal

New SS-50C signal

left to right)

1

1200 baud

1200 baud or SO

2

600 baud

600/4800 baud or SI

3

300 baud

300 baud or S2

4

150 baud

150/9600 or S3

5

110 baud

110 baud or BUS REQ’

6

HALT’

HALT'

7

01

BS

8

BA

BA

9

RESET’

RESET’

10

R/W’

R/W'

11

VMA’

VMA’

12

02

E

13

UD1

Q’

14

UD2

FIRQ’

15

IRQ’

IRQ’

16

NMI’

BUSY’

17

M.RST’

M.RDY

18

-

19

+ 12 VOLTS

+ 16 VOLTS

20

-12 VOLTS

-16 VOLTS

21-23

+ 8 VOLTS

+ 8 VOLTS

24-26

GROUND

GROUND

27-42

A0 through A15

A0 through A15

43-50

D7’ through DO’

D7’ through DO’

Table 1. Old and new 50-pin buses.

Pin no. (from

Old SS-30 signal

New SS-30C signal

front to back)

1

I/O PORT SELECT’

I/O PORT SELECT’

2

RESET’

RESET’

3

110 baud

110 baud

4

150 baud

150 or 9600 baud

5

300 baud

300 baud

6

600 baud

600 or 4800 baud

7

1200 baud

1200 baud

8-9

+ 8 VOLTS

+ 8 VOLTS

10

R/W’

R/W’

11

02

E’

12-19

D7 through DO

D7 through DO

20

RSI

RSI

21

RS2

RS2

22

IRQ’

IRQ’

23

NMI’

FIRQ’

24

25-26

GROUND

GROUND

27

+ 12 VOLTS

+ 16 VOLTS

28

-12 VOLTS

-16 VOLTS

29

UD4

RS3

30

UD3

RS2

Table 2. Old and new 30-pin buses.

meetings of 6800 manufacturers
to hammer out what the stan-
dard SS-50 bus should be and
what, if any, modifications
should be made to it in the
future. At that time, there was a
consensus on three possible
versions of the bus: SS-50A, SS-
50 B and SS-50C. SWTP is now
using a slightly modified SS-
50C bus in their 6809 system.
Table 1 shows exactly what
lines are used on the old and
new bus. In the same way,
Table 2 shows the changes to
the 30-pin I/O bus.

We’ve already described
some of the SS-50C changes.
Let’s now look at the others.

On the 50-pin bus, pins 16

and 17 were NMI’ and M.RST’
on the old bus. What happened
to them? They are still on the
MP-09 CPU board, but they are
brought to connectors at the
top of the board. M.RST (master
reset) now must be wired
through a short cable to the
RESET switch on the front
panel. Likewise, NMI’ must now
be wired through a separate
cable. In noisy environments,
shielded cable may be needed.

The 12-volt supplies have
been replaced with 16-volt sup-
plies. As was described in the
first installment of this series
(“Some Thoughts on the SWTP
Computer System,” March 1979,
p. 58), these supplies have

always been marginal, and
changing from 12 volts to 16
should Improve things. But
watch out! Some add-on
boards requiring 12 volts have,
in the past, been designed
without on-board regulators,
relying on the 12-volt supplies’
proximity to the required
values. To use them in a new
system, you will have to install
the missing regulators, or risk
serious damage to them.

The 50-pin bus also shows
another change in pins 1
through 4; four of the baud rate
signals can be replaced with
signals SO through S4, four
additional address lines that
allow the system to be ex-
panded up to an advertised
384K of memory . . . and per-
haps more.

MP-09 Addressing Circuitry

The big change, which af-
fects the whole system and
may make it impossible to
switch back and forth between
the 6800 CPU board and a new
6809 CPU board, is in address-
ing. The MP-09 CPU board,
combined with the SBUG
monitor, has an interesting
combination of hardware and
software for memory and I/O
addressing.

The MP-09 board has sockets
for two 74LS189 16 X 8 TTL
RAMs: One of these (IC11),
called the DAT (dynamic ad-
dress translator), is required;
the other (IC8) is optional, to be

used for extended addressing.

Dynamic Address Translator

The address translator is of
immediate interest. It is basi-
cally a 16 x 4 RAM, which is ad-
dressed as locations FFF0
through FFFF. You may note
that this overlaps the monitor,
which is FC00-FFFF. But the
difference is that the monitor is
a read-only memory, whereas
the RAM is write-only memory.
The two do not conflict, even
though they share the same ad-
dress, since a read and a write
can never occur at the same
time. When a load is executed
from FFFF, for instance, only
the ROM is affected. When a
store is executed to FFFF, only
the RAM is affected. Since this
RAM only stores four bits, only
the rightmost four bits of the
number being stored into
FFF0-FFFF actually get stored
in the DAT RAM.

Fig. 1 shows a simplified
diagram of the DAT. The ad-
dress inputs into the RAM are
connected to the address bus
through a 74157 selector, IC10.
IC10 acts as a two-position
switch, connecting either its
four A inputs or its four B inputs
to the RAM.

When the RAM is being writ-
ten into, the selector is switched
to the B inputs. The rightmost
four bits of the address— shown
as A3 through A0 at the bottom
of the diagram— are fed through
the selector to the RAM. Since

Fig. 1. Dynamic address translator.

58 Microcomputing January 1980

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Microcomputing January 1960 69

the four bits represent the right-
most hex digit in the address
(FFFO through FFFF for the
RAM), they determine where in
that RAM data will be written.
The data input itself comes from
the lower four bits of the data
bus.

Writing into the RAM in a
simple 6809 system actually
takes place fairly seldom —
SBUG-E writes into the RAM
once, just after it is started up.
The rest of the time, the ad-
dress selector is switched to
the A inputs, and the RAM is
more or less permanently
placed into a read-only mode.
But note that the data read
(coming from the RAM’s data
out pins) doesn’t go to the data
bus; it goes to the address bus!

As you can see from Fig. 1,
the top four bits of the 6809’s
address outputs, A15 through
A12, don’t go directly out to the
address bus; instead, they go
to the selector, and through it
to the address inputs of the
RAM. The top four bits of the
address bus come out of the
RAM’s data outputs. So the top
four bits of the address bus on
the right need not necessarily
be the same as the top four bits
of what the 6809 is putting out.

There are two new words ap-
plied to addresses here. The ad-
dress coming out of the 6809 —
the address the program
“thinks” is being called — is
the logical address. The ad-
dress that actually appears on
the address bus and goes to
memory and I/O is called the
physical address. In 6800
systems, which have no DAT,
the logical and physical ad-
dresses are always the same.
Here they may be the same, but
not necessarily. For instance,
if every location of the IC11
RAM is programmed to hold a
binary 0000, then regardless of
what logical address the 6809
is outputting, the physical ad-
dress will always start with a
binary 0000.

On the other hand, if location
0000 of IC11 is programmed to
0000, location 0001 holds 0001,
and so on, up to location 1111
holding 1111. Then the phys-
ical and the logical address
will always be the same, be-
cause the data coming out of

the RAM will always be the
same as the address going into
it.

Since the DAT circuit works
on the high-order four bits, it
changes the leftmost hex digit
of a 16-bit address into some
other digit. For instance, it can
change a logical 2 into a
physical 3, so that every
reference to locations 2000-
2FFF will actually involve mem-
ory at 3000-3FFF instead. Since
each 4K block of memory has a
different first hex digit, the DAT
circuit can move 4K blocks of
memory around.

When a 6809 system using
SBUG-E is first brought up, the
monitor initializes the DAT
RAM into a known memory pat-
tern and then goes through
memory, one 4K block at a time,
testing each block to see if it
actually has RAM there. In this
way, it determines which
physical addresses correspond
to real RAM memory. Then,
regardless of whether this RAM
is in adjacent 4K blocks or not,
the monitor readdresses these
blocks, via the DAT RAM, to
make them adjacent. Hence,
regardless of how the RAM
boards in a system are ad-
dressed, the DAT will readdress
them where it wants them, as
long as two boards don’t have
the same address.

But this is not the main pur-
pose; the word “dynamic” in
DAT is important too. This read-
dressing can take place dynam-
ically, that is, as the system is
running. SBUG-E doesn’t seem
involved here, but other system
programs can change the DAT
addressing too. This would oc-
cur, for instance, in time-
sharing.

When two or more users are
being time-shared on a com-
puter, they each get a chunk of
time, called a slice, during
which their program runs.
When the time is up for one
user, his program is stopped
and another’s starts. This “con-
text switch” can be done in
several ways. The DAT can
simply be reprogrammed so
that the memory blocks as-
signed to user 1 are simply de-
leted from the DAT RAM, and
the memory assigned to user 2
is relocated, via the DAT RAM,

to the same logical memory ad-
dresses previously held by user
1 . If this is done at regular inter-
vals — every 60th of a second,
for instance — each user will
get fast enough response that
he will be unaware he is sharing
time on the machine with some-
one else.

The context switching could,
of course, be done in some
other way too. For instance, all
the memory assigned to user 1
could be written out to disk,
and another user’s program
and data could be read in from
the disk. This procedure would
take much longer than leaving
the material in memory but
simply readdressing it some-
where out of the way.

Dynamic address translation
such as this is of limited use
if you’re limited to somewhere
between 32K and 64K of memo-
ry. The MP-09 CPU board has
facilities for adding much more
memory than that.

The Extended Address Bus

As mentioned earlier, there is
room for another 74LS189
RAM; this one is optional. This
RAM is IC8, which is wired up in
a similar way to the DAT RAM in
Fig. 1. The only differences are
that the data into the RAM
comes from the other four bits
of the data bus (D5 through D7)
and that the data outputs
(S0-S3), instead of being part of
the 16-bit address bus, become
an extension of it. Counting
these four bits, the extended
address bus becomes 20 bits
wide. With 20 bits, we could ad-
dress 1,048,576 different
memory locations for a total of
1024K, instead of just 64K.

Essentially, the lower 16 ad-
dress lines address a 64K block
of memory, while the four new
address lines, SO through S3,
provide for 16 such blocks.
Let’s call each of these 64K
blocks a page.

A change from one 64K page
to another can be done simply
by storing a new 4-bit page
number into that optional RAM.
But a program obviously can’t
flit back and forth between
pages, since this would greatly
slow everything down. Hence,
going from one page to another
is reserved for special occa-

sions, such as during complete
context switches.

Actually, the system can’t
really be expanded to the full
1024K of memory. Some memo-
ry addresses are still needed
for I/O, a monitor and perhaps
other important programs such
as a disk operating system, as
well as their required RAMs.
Hence, a certain amount of
RAM, ROM and I/O will have to
exist on every page and should
ideally have the same ad-
dresses on every page. This
eliminates a large area of each
page from being used for nor-
mal processing, so that the
total amount of memory is
quite a bit less. SWTP expects
the limitation to be 384K total,
and their reasons are not yet
entirely clear.

Note that making proper use
of both the dynamic address
translator as well as extended
addressing up to 384K of
memory requires two things:
sophisticated software to keep
track of what’s going on and
where and a need to do all this.
There are a great many applica-
tions where the need for all this
complexity in hardware and
software is simply not there.

One hardware change must
be made if the address bus is to
be extended. As shown in Table
1, the four new address bits, SO
through S3, are sent along four
lines on the 50-pin bus, which
are normally used for baud
rates. On the CPU board, this is
accomplished simply by un-
plugging the MC14411 baud
rate generator when the op-
tional memory extension RAM is
plugged in.

But since serial interface
cards still need baud rates,
these now have to come from
somewhere else. SWTP is
therefore offering a baud rate
generator card, which plugs in-
to the 30-pin I/O bus and pro-
vides those signals. A few cuts
on the motherboard are re-
quired to isolate the baud rate
lines on the 50-pin bus from
those on the 30-pin bus.

The SBUG-E Monitor

SBUG-E is the new SWTP
monitor ROM. It is a
2716-compatible 2K by 8 ROM,
which resides on the MP-09

60 Microcomputing January 1980

CPU board, addressed at
F800-FFFF.

SBUG-E has two possible
operating modes. As supplied,
it permits up to 56K of memory
to be installed on the main
memory page. But this requires
that I/O addresses be moved
from the 8000 region, which
they occupy in a standard 6800
system, up to E000. (It’s not en-
tirely obvious why this should
be needed, considering that the
DAT circuit should be able to
move I/O at will. But one reason
is that the monitor has no easy
way of detecting, via program-
ming, where the I/O is.) Hence a
system will have to be modified
to work with a standard SBUG-
E; then it will not work with a
6800 CPU board.

However, by changing one
byte in SBUG-E, you can retain
I/O at address 8000, but then
the memory is limited to just
40 K total (32 K and 8K, combined
by the DAT circuit). This requires
that SBUG-E be read into mem-

change to the motherboard.

2. At least 4K of RAM
memory, physically addressed
anywhere below DFFF.

Wherever that RAM is, SBUG-
E will find it and relocate it, us-
ing the DAT, to logical address
D000-DFFF. The region from
D800 up to DFFF will then be
used as the monitor scratch-
pad. (A disk system will need at
least 8K just to boot the disk,
and most applications would
obviously need much more.)

SBUG-E can be thought of as
divided into four areas: the user
command processor, a set of
user-callable subroutines, an
interrupt and breakpoint
handler and an initializer
routine concerned with, among
others, initializing the DAT and
the various ports.

The user command pro-
cessor is a greatly expanded
version of what MIKBUG or
SWTBUG had. Table 3 lists the
commands from the keyboard
that SBUG-E will respond to.

Control-A —

Alter the A accumulator

Control-B —

Alter the B accumulator

Control-C —

Alter the condition codes register

Control-D —

Alter direct page register

Control-P —

Alter program counter

Control-U —

Alter user stack pointer

Control-X —

Alter X index register

Control-Y —

Alter Y index register

B hhhh —

Set breakpoint at location hhhh

D —

Boot an SWTP 8-inch floppy system

U —

Boot an SWTP 5-inch floppy system

E ssss*eeee —

Examine memory from starting address
ssss to ending address eeee

G —

Continue from a breakpoint

L —

Load tape

M hhhh —

Alter contents of memory location hhhh

P ssss-eeee —

Punch tape using specified addresses

Q ssss-eeee —

Test memory locations ssss through eeee

R —

Display register contents

S —

Display contents of stack

X —

Remove any existing breakpoints

Table 3. SBUG-E commands.

ory, that one byte be modified
and a new monitor be burned in-
to a 2716 EPROM. (Instructions
are in the SBUG-E manual.) Even
then, though, there are enough
other small changes that the
modified system will still not
work with an old 6800 CPU
board.

The standard SBUG-E re-
quires a system configured like
this:

1. An MP-S serial interface
plugged into port 1 and I/O ad-
dressed at E000. This requires a

User-callable subroutines
now use an address table at the
very start of the monitor, loca-
tions F800 and up, to point to
each subroutine. This allows
monitors to be easily updated
without having to go through
contortions to keep all starting
addresses the same as In
previous versions. Standard
subroutines such as INEEE,
OUTEEE or PDATA exist (some
with new names), as well as a
few new ones: INCHECK
checks if a character is waiting

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Microcomputing January 1980 61

at the control interface; PCRLF
prints a carriage-return and
line-feed; LRA finds out what
physical address a logical ad-
dress corresponds to.

Finally, the interrupt and
breakpoint handlers are written
in a way that the interrupt
system can more easily be
used for user programs. There
are three SWI instructions in
the 6809, and each is provided a
different interrupt vector ad-
dress in RAM.

Modifications to Use
MP-09/SBUG-E

In order to plug an MP-09 CPU
board into an existing 6800
computer, you have to make a
number of modifications. Let’s
describe them very briefly; they
are covered more thoroughly in
the MP-09 manual.

If 40 K of memory is enough
(32K in addresses 0000-7FFF
and 8K somewhere else, but the
DAT will make it appear con-
tinuous), then the I/O address
decoding on the motherboard
need not be changed, but
SBUG-E will have to be modi-
fied and reprogrammed into a
2716. (This will obviously have
to be done before the 6800 CPU
board is unplugged.) The MF-68
mini-floppy is supported in this
case, but the DMAF full-size
floppy will not work like this.

To expand above 40K or to
use the DMAF floppy, all I/O
must be moved from 8000 up to
E000. This requires that the
motherboard have several
traces cut and several new
wires added. (This modification
is much more complicated on
the older MP-B board than the
newer MP-B2 motherboard.)

In either case, the RESET
switch from the front panel will
have to be rewired from the
motherboard; it connects
directly to a connector at the
top of the CPU board. Another
motherboard change will in-
volve the NMI and FIRQ con-
nections, which are now dif-
ferent.

If a DMAF1 disk controller
board is used, its addressing
circuits will need to be changed
so the disk can be addressed at
F000-F3FF, instead of the
9000-93 FF used in 6800 sys-
tems. But note: Once this is

Many think that SWTP has
gone too far. Their system is
versatile, but by taking such a
gigantic step, they are placing a
burden on those who want
to convert existing systems.

done, you cannot plug your
6800 CPU board back in. It’s not
exactly an irreversible change
— you can go back — but it’s
just as much work to go back as
it is to switch to the MP-09 in
the first place. Hence, before
switching to the 6809, it would
be a good idea to make sure
that you have all your software
ready: BASIC, assembler, editor,
processor, disk operating sys-
tem, disassembler, utilities.
That’s a tall order.

Alternative 6809 Approaches

Private conversations with
many people involved in 6800
hardware and software in-
dicate that many think SWTP
has gone too far. Their sys-
tem is versatile, but by tak-
ing such a gigantic step, they
are placing a tremendous
burden on those people who
want to convert existing
systems.

As an example of what I’m
talking about, consider my
own system. Since I have some
nonstandard I/O equipment,
such as a Selectric typewriter, I
have a number of I/O subrou-
tines in 2716 EPROMs on my
MP-A2 CPU board. They are
presently addressed from C000
through CFFF.

There are extra EPROM
sockets on the MP-09 board,
but as mentioned above, they
cannot be used because their
addresses conflict with system
addresses. That’s easy, you
say. Either modify the CPU
board to change the addresses
or else install a separate
EPROM board.

That raises some questions,

though. What will SBUG-E do
with that EPROM? Will the
dynamic address translator
move its addresses to some
other place in memory? Will
that address be the same every
time I power up the system?
Will it be moved dynamically
around with time? Or, worse
yet, will the DAT simply ignore
my EPROM and assign no ad-
dresses to it at all?

These questions apply equal-
ly to non-SWTP hardware. If
you have an SSB or Percom
disk, where will the EPROM be?
If you have a parallel inter-
face for a paper tape reader,
or whatever, where will the
DAT put it? It sure makes it dif-
ficult for SWTP competitors
to offer any kind of hardware
or software. Every customer’s
DAT might assign different ad-
dresses to it! For this rea-
son, there are some other ap-
proaches.

The Percom 6809 Boards

Percom Data Company has
two 6809 boards in the works:
One is a simple adapter for
plugging a 6809 into an existing
6800 CPU board; the other is a
completely new 6809 board.

The 6809/6800 adapter board
was described in the August
1979 issue of 68 Micro Journal
in an article by Byron Seas-
trunk. It contains a 6809, two
ICs containing a few gates and
inverters, a crystal and two
resistors. The circuit, which
was published in the 68 Micro
article, mounts on an MP-A2
CPU board and plugs Into the
socket that originally held the
6800.

The circuit could be built
from the article or from a $69.95
kit available from Percom.
Either way, though, you need a
6809-based monitor. Percom is
also offering their PSYMON on
either a 2716 ($69.95) or on a
Percom diskette ($29.95) for
burning your own EPROM. Us-
ing it with an MP-A2 board is
easy sincethe monitor can plug
right into it. For use with an MP-
A board, you’d need another
EPROM board, plus a few cuts
on the MP-A board to discon-
nect its own ROM socket.

Use of this adapter board
still doesn’t make it easy to
switch back and forth between
a 6800 and a 6809, but at least it
does not require modifying the
motherboard or memory
boards. I suppose the best ap-
proach would be to wire up a
separate MP-A2 board just for
use with the 6809 adapter and
then switch entire CPU boards.
(Notice: You can’t do that with
the SWTP 6809 board because
the motherboard and bus must
be changed and are therefore
no longer compatible.)

The other Percom board is a
completely new 6809 CPU
board. Percom’s major aim was
to have a CPU board that was
completely compatible with ex-
isting hardware, yet had some
new features of its own. It has
enough jumpers so it can be
configured either to use exactly
the same bus as a 6800 system
or to use a bus very much like
the modified SS-50C bus used
by SWTP.

PSYMON, Percom’s monitor,
lies at addresses FC00-FFFF.
Right on the CPU board are a
parallel port at F7FC-F7FF and
a serial port whose ACIA is at
F7FA-F7FB. Two 2114 RAMs
on the CPU board provide IK of
RAM at F000-F3FF. All these
addresses are fully decoded, so
that other parts of this address
range can be used for other pur-
poses without interference.

Percom also is introducing a
video board they call the Elec-
tric Window (EW). Their CPU
board and monitor are set up to
use the EW in the following
way. When first powered up,
PSYMON checks the video
board’s addresses to see if it is
there. If the EW is connected,

62 Microcomputing January 1980

then it configures itself to use
the EW foroutput and the paral-
lel port on the CPU board for
keyboard Input. The CPU board
has IK of RAM, so that the
CPU/EW combinations can run
programs all by itself.

If the EW is not connected,
then PSYMON configures itself
to use the serial port on the
CPU board for I/O. There is a
connector at the top of the
board exactly like the one at the
top of an MP-S serial interface
card, so the terminal is just
unplugged from the MP-S into
the CPU board. The CPU board
has baud rate generators, so,
again, this one board can run
programs.

Percom’s CPU board does
not have the dynamic address
translator, since Gimix, SSB,
Percom and other manufac-
turers offer devices, such as
disk controllers, that need to
know what addresses they are
at. Since the SWTP monitor and
DAT circuit put them where
they want to, the DAT circuit on
an SWTP CPU board would
have to be disabled anyway to
bring up the system. So Percom
omits the DAT.

But there is provision for ex-
tended addressing. Normally,
the CPU board’s baud rate
generator feeds its own ACIA
as well as the baud rate lines on
the bus. If no external serial in-
terfaces are needed, then the
baud rate lines and the buffer
on the CPU board used to drive
them will be used for extended
addressing.

With just 32K of memory
from 0000-7FFF, all the regular
I/O can be left at 8000 (except
for the terminal, which is now
plugged into the CPU board).
Otherwise, by modifying the
motherboard, you can plug in
up to 60K of memory if the I/O is
moved up to the F000 region.

PSYMON comes in a 2708
EPROM and fits into one of two
2708 sockets on the CPU board;
the other socket can be used
for extended routines. But the
two 2708 sockets can be
jumpered to use either the Intel
5-volt 2716 or the Tl TMS-2716,
for a total of 4K of ROM. Nor-
mally, though, these sockets
are addressed at F800-FFFF
for 2708s, and the onboard IK

RAM is at F000-F3FF. The Elec-
tric Window would be at E800.

PSYMON is quite a bit
simpler than SWTP’s SBUG-E.
It occupies 1 K at the very top of
memory, but as soon as it ini-
tializes, it checks whether there
is another ROM plugged into
the other ROM socket. If so,
it jumps to that ROM. Hence,
PYSMON can be easily ex-
tended for more commands just
by plugging in another 1C.

PSYMON’s Basic Command
Functions

Memory examine is similar to
MIKBUG’s, but it saves the last
address you looked at. It
checks for bad memory, but on-
ly prints a question mark when
it finds a location that won’t
write properly. This is done so
that it is easier to change con-
tents of I/O port registers.

Load and Save are also
similar to MIKBUG, except that
the load prompts for beginning
and ending address instead of
having to use addresses A002
through A005.

Up to ten breakpoints can be
set into a program. They can be
set and unset selectively or all
at once. A command exists to
print out the addresses of all
outstanding breakpoints.
When a breakpoint is en-
countered in a program, it is
deleted.

Register dump and GOTO are
similar to those of 6800
monitors.

Percom has a different
philosophy on monitors and
I/O. Their thought is that
monitors should be simple, so
they don’t try to anticipate all
the possible I/O and memory
combinations users might
hook up to the system. They
did, however, try to make their
I/O somewhat device-indepen-
dent by having a small area of
memory in RAM, called a DCB,
or device control block,
devoted to each I/O device. This
DCB specifies the type of each
serial or parallel device and
where it is addressed. To
change an I/O device, it’s only
necessary to change the DCB
pointer in the scratchpad RAM.
This allows echoing and l/O-to-
l/O transfer by manipulating
the DCBs.

GIVE YOUR TRS-80 WHAT IT DESERVES

All tapes $10.00 each, on cassette.
C.O.D. orders accepted
Choose Level I or II.

A television station in Florida chose our Bioforecast program (catalog #
CS-1) to use in a special news broadcast during the November 1978 state-
wide political elections. Many think ours is the best biorhythm program ever
written. And it loads and executes in less than 4K!

One customer is using ou r Orbit programs (catalog # CS-2) to help him in
the weather satellite work he does for the Air Force.

Recreation centers, schools, businesses, doctors, and housewives are
using our Lend Out program. Lend Out (catalog # CS-7) keeps track of things
loaned out to people. Its high utility, together with its many features and
ease of use. have made it a best seller.

And speaking of best sellers . . .

Our Turkey Buzzard game (catalog # GT-4) has made an even bigger
splash than we expected. It is a game that has everything: a detailed
scenario, character animation, and a general arcade style. It s chocked full
of dangers and comic pitfalls. No wonder there are those who say it may be
the most successful work ever to combine a continually changing plot with
all TRS-80 graphics capabilities. Already it is becoming a classic among
classics.

All of the above programs will execute in less than 4K RAM! You can't get
those programs from any other company. We invented them and only we
own the rights to them. Sure you can buy one of those cheap “software
library" deals, but most of the programs they feature can be found in books.
Books you can check out from your public library for nothing.

So for something truly different for your computer, look to the creative
software company.

Send SASE to receive the product list faster.

6 Mill St. Compurex O

PO Box 536 Inman SC 29349

LET YOUR TRS-80 HELP YOU FIGHT]
THE HIGH COST OF LIVING!!

Inflation is robbing every consumer of the purchasing power of his dollar.
There is no known way to completely stop this invisible bandit; but now, using
your computer, you can minimize some of the bad effects on your house-hold
budget with the Computrex HOMEBREW PRODUCTS PROGRAM! With the in-
formation this cassette software package provides, the average consumer can
save as much as 50 to 90 percent on the price of common domestic products
(from antiperspirant to window cleaner). This is because your microcomputer
can tell you simple, easy ways to make these products from scratch in your
home. Most products have low-cost ingredients which you can obtain at your
local grocer, drugstore, or building supplier. The operation of this program is so
obvious and straightforward, the documentation so complete and clear, that
anyone can use this program effectively almost as soon as they receive it! No
knowledge of computers is required.

Features:

1 ) Finds a product’s formula or recipe by either the product’s name or category
use.

2) It’s fast! No long waits for information.

3) When asked 7 the program gives a complete listing of all products for which it
has formulas, and also displays their categories.

4) Special test feature which can check to see if the entire program loaded
properly.

5) More!

The HOMEBREW PRODUCTS PROGRAM is a Computrex exclusive. You
can’t get it from any other company. So show everyone that that computer of
yours is more than just a game-playing toy. Order your copy of this unique soft-
ware package today! Price: $16.95 (requires 16K LEV II)

See “NEW PRODUCTS” section of the November Issue of this magazine.

Also check back issues for ads describing some of our other fine products.

Note: We do not sell software through dealers and stores because our anti-
plagiarism system will only work effectively with an exclusively mail-
order market.

C.O.D. Orders accepted. Phone # in our Oct ad is incorrect. Please
Phone: 1 -803-472-2083 us ® # ,n th,s ad t0 contact Computrex

Send S.A.S.E. to receive our product list faster.

Compuirex

6 Mill St. C86

PO Box 536 Inman SC 29349 HZ

iS Reader Service— see page 227

Microcomputing January 1980 63

Percom is trying to make
their CPU board versatile
enough so that most SWTP and
TSC software is likely to run on
it. On the other hand, they also
have to support their own disk
systems, which require dif-
ferent disk drivers.

Their past approach in this
respect has been to offer their
own software (they have an ex-
cellent assembler and random
BASIC, for instance), adapt
other companies’ software to
run on their systems (Ed
Smith’s software is a good ex-
ample), and as a last resort,
simply provide at either low
cost or no cost at all patches to
other people’s software to
make it work on their disks (for
instance, they have patches to
Microware’s cassette A/BASIC,
Smoke Signal Broadcasting’s
Source Generator and TSC’s
Text Editor and Processor). It’s
a fairly safe bet that they will do
the same for their 6809 CPU
board.

The Gimix CPU Board

Another contender in the 6809
CPU board race is Gimix (1337
West 37th Place, Chicago IL
60609).

About a year ago, Gimix in-
troduced their new 6800 main-
frame. Compared with the
cabinets SWTP users have got-
ten used to, this one is built like
a tank. (Even the screw holes
line up.) The power supply itself
probably weighs more than the
complete computer of “the
other brand.” Needless to say,
the price is several times
higher, but for industrial users
this may not be significant.

About the middle of 1979,
Gimix started to ship this main-
frame with their new 6800/6809
motherboard. This board has
some of the features that will
be needed in 6809 systems of
the future.

Aside from a variety of
jumpers to give all sorts of op-
tions, Gimix puts the baud rate
generator on the motherboard.
This releases the five baud rate
lines on the 50-pin bus, yet pro-
vides the required signals to I/O
boards.

If you’ve noticed the RS2 and
RS3 lines in Table 2, you may
have wondered what they were.

6800 systems had a pair of lines
called RS0 and RSI , which were
actually two buffered lines
from the address bus and were
used by the I/O interfaces to
give each I/O slot up to four ad-
dresses. For instance, you may
remember that an MP-C control
interface in port 1 had four ad-
dresses, 8004 through 8007,
which were selected via the RS
lines.

But there were some cases
where four addresses per port
were not enough. For instance,
the SWTP MF-68 disk controller
required a jumper in port 5, so
that some of the addresses of
port 5 were available to the disk

ones as well) can be used.

Now, to go with their new
cabinet and motherboard,
Gimix has designed a CPU
board. Details are a bit sketchy
at the time of writing, but it is
obvious that Gimix is going
another route. Instead of
writing their own software to fit
the board, they are designing
the board to fit a major soft-
ware undertaking that Mo-
torola and Microware Systems
Corp. are working on.

What About Software?

TSC has already announced
their initial 6809 programs. At
first glance, they appear to be

(ft

Everyone must make his own
decisions on conversion to the
6809, but my own thought is that
this is the time to sit back and
wait for the dust to settle. Per-
haps you shouldn’t switch at all.

JW

interface in port 6.

The new 6809 systems an-
ticipate those problems by pro-
viding two more address lines
to the I/O ports, so that each I/O
port can have up to 16 ad-
dresses. The Gimix mother-
board also has those lines; its
I/O block is therefore 32 bytes
long if only four addresses are
used per port (four addresses
times eight ports), 64 bytes if
eight addresses are used or
128 bytes if 16 addresses are
used. The decoding is thorough
enough that these are all the ad-
dresses that I/O requires.

The Gimix motherboard also
has an optional circuit that pro-
vides the appropriate Memory
Ready (M.RDY) signal to slow
down the CPU whenever an I/O
operation is being done. The
idea here is to give I/O a bit of
extra time if a fast 2 MHz clock
rate is used, so that older I/O
boards (and probably slower

simply reassembled versions of
their 6800 programs, with some
updating to adjust such factors
as timing loops. Their 6809 pro-
grams include:

6809 FLEX with Editor and
Assembler. This requires mem-
ory at C000 and costs $90.

The Text Editor ($35) and the
Assembler ($40) are available
separately in cassette form.

TSC BASIC at $65 should
turn in a stunning performance
in the speed department. Unfor-
tunately, with just six-digit
math, it’s a little limited for any
kind of business application.

The 6809 Debug Package
($75) for tracing and debugging
programs.

TSC’s advertising doesn’t
answer some important ques-
tions, such as whether their
new FLEX will read text and
binary files from disks written
on a 6800 system. That’s crucial
if you’re going to convert some

of your old 6800 software to
the 6809.

Another 6809 product is a
6809 simulator that will run on a
6800; it’s available from Micro
Works.

Two products that I think will
be essential are a 6809
assembler that will run on a
6800 and a 6800 disassembler
that will run on a 6809. Nobody
seems to be offering them, but
for anyone who wants to con-
vert his 6800 programs to a
6809, they would be very useful.

Perhaps the most ambitious
6809 software project is the
one being developed jointly by
Microware and Motorola. It is to
be a fast and versatile BASIC,
which Motorola intends to sell
in ROM at a low price. (Gimix is
waiting for it to appear before
finalizing their CPU board.
Wonder whether it will be com-
patible with the SWTP ap-
proach.)

The BASIC, which is called
BASIC-09, is an incremental
compiler; that is, each line is
partially translated as it is
entered. This also means that
syntax errors are caught right
away.

It is meant to be an expanded
BASIC, which has all of the
“standard” BASIC features, as
well as some versatile exten-
sions to make it more like
PASCAL. In fact, Motorola
hopes that it will become more
popular than PASCAL. Much
like PASCAL, it will have
I F . . . TH EN . . . ELSE;
WHILE ... DO; REPEAT . . .
UNTIL-type statements. It’s
supposed to be procedure-
oriented; that is, a program is
divided up into more-or-less in-
dependent procedures, each of
which handles a specific job.
Each procedure can have vari-
ables that are strictly local and
whose names can be reused
elsewhere without conflict.
Procedures are called by a
name, along with some argu-
ments for input or output from
the procedure. Variable names
can be any length.

It is also supposed to have
user-defined data structures;
for instance, a data structure
can be thought of as a special-
purpose array whose entries
have different characteristics.

64 Microcomputing January 1980

BASIC-09 has many other fea-
tures, but the final language will
be determined by how much Mo-
torola can squeeze into one
ROM.

The operating system, OS-09,
is also being worked on but
may not be available until later.
It’s designed for multitasking
— running several different
programs (tasks) at the same
time, while they share pro-
grams, memory and I/O devices
to some extent. That is quite
an interesting, and advanced,
concept. The question is, will
it work with the XYZ CPU
board?

Standards and Compatibility

The problem with all this is
that different manufacturers
are seemingly headed in dif-
ferent directions. Once you
pick a particular hardware ap-
proach, you are committing
yourself to a whole system. It’s
like buying a Kirnura camera
. . . only Kirnura lenses will fit,
and only Kirnura makes the
right size film. Unfortunately,
this wiil bring you down to the
level of all our S-100 friends,
who have that problem all the
time. It kills the one feature of
our 6800 systems: Every 6800
system is like any other one in
terms of addresses, and so if
you buy a new piece of hard-
ware or software, you need only
plug it in, and it will work.

Everyone must make his own

decisions on conversion to the
6809, but my own thought is that
this is the time to sit back and
wait for the dust to settle. And
perhaps you shouldn’t switch at
all.

For me, switching to the 6809
processor would obsolete all
my software investment, which
at this point is several hundred
dollars’ worth. Although the
6809 is supposedly compatible
with the 6800 in software, its
machine language is different.
Hence all my software would
have to be reassembled to
work. For those programs for
which I have the source code,
this is feasible. But for the rest
it would be very difficult.

Even so, much of this
reassembly would have to be
done before switching CPUs,
so that the instant the new 6809
CPU was up, I would have all of
the software I needed— a mon-
itor, disk operating system,
editor. Since it is likely that
simple reassembly might not
be enough, I then visualize long
periods of switching back and
forth between new and old
CPUs before everything
works ... not to mention that I
would need a cross-assembler
— an assembler that translates
6809 code but runs on the 6800.

I am sufficiently happy with
my present system that I’m not
sure I’d want to go through this
hassle. Just talk to any com-
mercial data processing man-

ager who went through the job
of converting from the IBM 1401
to an IBM 360 back in the 60s.
There are some harrowing tales
there.

I also have a hunch that the
days of reasonably priced soft-
ware are over. One of the big
pluses that often swung a sale
toward the SWTP system was
the price of BASIC and Cores.
What other system could boast
an excellent— if slow— BASIC
for $10 or an editor and assem-
bler for $15? Robert Uiterwik
wrote our SWTP BASIC more
out of love than for any interest
in the cold, hard stuff. And
SWTP was in the hardware
business; software was an add-
ed incentive, not a business for
them. Considering copying
costs and all that, they proba-
bly lost money on every
cassette they sold.

But look at the software
market now. SWTP is, I think,
leaving the software market
altogether. The latest TSC
BASIC is $50 or so; Microsoft’s
quoted price for their 6800
BASIC is $50,000.

To some extent, the nature of
the customer has changed. Pre-
viously, you bought BASIC for
$10, and if it had bugs, then a
few months later you bought
the next version. In the mean-
time, you changed your pro-
gram so it wouldn’t be bothered
by the bugs.

But now, with the small-

business user in the act, that
won’t happen. If there is a bug,
he will expect to be able to call
up the software house and get
a fix. When a patch comes up,
he wants it sent to him auto-
matically. Naturally, that
changes the price the software
house can charge.

So, assuming the higher soft-
ware prices that seem to be
coming, I suspect that the price
for switching to a 6809 system
will break down as shown in
Table 4.

Maybe I’m being overly
pessimistic, but the question
remains: Is it going to be worth
it? To paraphrase a popular
song, “What’ll we have that we
ain’t got now?’’

Next month, we will discuss
some techniques for single-
drive disk systems, converting
the SWTP 2716 EPROM pro-
grammer to work on 2708
EPROMs and other EPROM
boards and programs. ■

Hardware (CPU Board)

$175

Software:

BASIC

$ 65

Editor

50

Assembler

30

Text Processor

50

Disassembler

50

Debug pack

75

DOS

50

Disk utilities

75

Software total

$445

Total

$620

Table 4.

Estimated cost of

switching to a 6809 system.

^X4

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Reader Service— see page 227

Microcomputing January 1980 65

Allan S. Joffe W3KBM
1005 Twining Rd.
Dresher PA 19025

Outer Limits Addition

This handle on programming lets you smash some of the limits on programming.

10 REM LARGE NUMBER ADD PROGRAM BY JAY JOFFE
20 REM MODIFIED BY W3KBM
25 CLEAR
30 CLS

40 CLEAR 2000 :REM ADDITION OF LARGE INTEGERS
50 DIM A(100)

60 DIM B(100)

70 DIM N$(100)

100 DIM T(100)

110 PRINT: PRINT

130 PRINT "THIS IS AN INTEGER PROGRAM. ..NO DECIMAL POINTS PLEASE"

140 PRINT "INSERT NUMBERS WHEN PROMPTED BY ?": GOTO 160

150 GOTO 140

160 GOSUB 340

170 GOSUB 400

180 PRINT " "

190 PRINT "A+B-";

200 GOSUB 560
210 GOSUB 630

220 FOR W = 2 TO 100: A(W)=0: B(W)=0 : NEXT W: GOTO 25
230 GOTO 140
240 GOSUB 400
250 GOSUB 630

260 FOR X= (101-LEN(N$)> TO 100

270 T (X) = ASC (MID$ (N$ , Y, 1) ) -48

280 IF T(X) > 9 OR T(X)^ 0 THEN GOTO 310

290 Y-Y+l

300 NEXT X :GOTO 330

310 PRINT "NON NUMERIC DATA"

320 FOR X - 1 to 440: NEXT X: RUN
330 RETURN
340 Y-l: N$-""

350 INPUT "A-";N$

360 SIZE=LEN(N$)

370 GOSUB 260
380 GOSUB 780
390 RETURN
400 Y-l: N$=""

410 INPUT "B=";N$

420 SIZE - SIZE-LEN(N$)

430 FOR J=1 TO SIZE
440 J$-J$+"0" :NEXT
450 N$=J$+N$

460 GOSUB 260
470 GOSUB 770
480 RETURN

490 FOR P= 100 TO 2 STEP -1
500 IF A(P)< 10 THEN GOTO 540
510 C= INT (A(P)/10)

520 A (P-1) -A(P-1)+C
530 A(P) -A(P) - ( 10 *C)

540 NEXT P
550 RETURN

560 FOR R = 2 TO 100
570 A(R) =A(R) + B(R)

580 NEXT
590 GOSUB 490
600 RETURN
610 GOSUB 720
620 N$=""

630 GOSUB 790
640 GOSUB 720
650 N$-""

660 FOR X- T(l) TO 100
670 N$-N$+CHR$ (A(X)-^48)

680 NEXT X

700 PRINT N$ : INPUT "PRESS ENTER TO CONTINUE";D$

710 RETURN

720 FOR X= 2 TO 100

730 IF T (X) -0 GOTO 750

740 T(l) -X : GOTO 760

750 NEXT X

760 RETURN

770 FOR X =1 TO 100: B(X)-T(X) : NEXT: RETURN
780 FOR X -1 TO 100 : A (X) =T(X) : NEXT : RETURN
790 FOR X -1 TO 100:T(X)-A(X) : NEXT: RETURN
800 END

Program listing .

O nce you get past certain
items, such as breathing,
eating and sleeping, it becomes
a bit sticky to define what else
may be of Universal importance.
For instance, as the owner of a
brand new TRS-80 Level II, you
may not care that you cannot
get last-digit accuracy with the
following addition problem: 99-
9999999888888888 + 2. 1 E + 1 8
Is what will be displayed on
your monitor. You can tell by in-
spection that the accuracy to
the last digit will show the real-
life answer to be 999999999888-
888890. Certainly, you will not
let “hitting a limit” cause you to
send your TRS-80 back to its
mother with a note asking,
“What gives?” It is all too true
that for practical folk the differ-
ence in the two answers is not
going to mean much.

However, for you fans of the
infinite, you folk of all persua-
sions that aspire to be pro-
grammers, limits are annoying.
They represent a chance to ex-
tend the capabilities of your
machine into the outer limits
and at the same time exercise
your skills at what it is really all
about, in other words, pro-
gramming.

The Program

By now you must be fairly
sure that there is a way to turn
your TRS-80 into a nitpicking,
last ditch, last digit, adding
fool. The Program listing here
provides one answer to the
problem.

The largest portion of this
program was produced by my
son, Jay, in response to my ini-
tial frustration with the basic
premise of it all: “Why can’t I
get this machine to do what I
think it should do rather than
what I think I told it to do?”
Examining the listing, be

aware that it is an integer pro ■

gram only. If you try to slip in a
decimal point, one of the nicely
nested subroutines will print
the message listed in line 310,
“Non Numeric Data,” and send
you back to the start. It will do
the same thing if your wander-
ing fingers should strike a letter
on your keyboard. The program,
fundamentally, puts the two
numbers to be added into
aligned arrays and then pro-
ceeds to add them and print out
an answer.

If you examine the listing
closely, you will see a variable
called SIZE, which first appears
in line 360. This line with its
companion lines inserts lead-
ing zeros into the appropriate
array cells that may or may not
be filled with pertinent numeri-
cal information. If you calcu-
late a sum with pencil and
paper, you do the same thing by
carefully aligning the numbers
one under the other so you can
properly add them. You do not
write in the leading zeros, but
your method is the same. You
can mentally ignore these
gaps, but if the computer is to
function properly it must fill in
those gaps, since it has no
imagination to help it while it
adds.

Consider line 340 in the pro-
gram— Y=1: N$ = “”. The “”
may possibly be unfamiliar and
lead to problems when you key
the program into your machine.
This symbol is composed of
two quote marks with no sepa-
ration as typed, and essentially
it provides a NULL, which re-
sets the value of N$ back to
zero.

Jay tends to lean toward a
type of structured program-
ming that may initially be hard
to follow due to the liberal use
of nested subroutines. You may
knock this approach, but it

does work well, i

66 Microcomputing January 1980

15 ISSUES FOR $15
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next published issue.)

January 1977

□ is the Z80 the Wave of the Present?

□Tiny BASIC

□ How a Memory Works

□ Software Exchange

□ Practical Microcomputer Programming Part 1 Logical
Instructions

□Well. Your Micro's Built . . where do you grow from here
□Computer Control of the World! . . turning ac powered
devices on and off with your computer
□Wire Wrapping

□ The Hobbyist's Operating System Part 1 Introduction
and Master Plan

□ Solving Some of the Software Interchange Problems
□Welcome to Assembly Language Programming

□ Programming? It's Simple'

□ Structured Programming

□Computers in Coif help for the handicapped
□Computer Widow

□What’s that Digital Croup Really Doing?

□ How to Use the New PR-40 Printer

□ Fire! ... let your micro call for help

□ A Teletype Alternative

□ Noboby Knows the Troubles I've Seen
□Structured BASIC A negative view by Dr. Kemeny. the

author of BASIC

□ Six Carnes on a Chip

February 1977

□ZAP!

□Chasing Those Naughty Bits
□Why So Many Computer Languages?

□ The Remarkable Apple Computer

□ Beware the Wumpus
□Chase!

□Will the Z-80 Crush All Competitors?

□ Practical Microcomputer Programming Part 2: Oper-
ating Systems

□ The Trouble with Mass Storage Systems

□ A Useful Loan Payment Program

□ Submarine! a game for the SR-52

□ The Hobbyist's Operating System Part 2: Interfacing
with the Monitor

□ Found: A Use for Your Computer! a clock program tor
the KIM

□Sophisticating a Surplus Keyboard

□ At the Races

□ RCA Tries Again . with the 1802
□8080 vs 370

□Cut 6800 Programming Time with this Extraordinary Pro-
gram

□7 x 9 = 56

□ Learning Computerese

□ How to WIN the Surplus Came
□Making Money Is Nice

□The 8080 You May Have Missed

□ The "Kill a Byte” Standard
□A 6800 Single Stepper

□ Computerized Statments

March 1977

□ Practical Microcomputer Programming Part 3: Soft-
ware m Tools

□ The Motorola Way! . . review of the MEK6800D1

□ Let's Hear It for the 680b!

□The Paper Tape Caper

□ Computers for Free!

□A New Approach to the 6800 . the Astral 2000

□ Journey into the CPU
□Only Five Senses

□ Floppy Disks

□ The Jupiter II

□ How to Win S25.000 of Your Own Money

□ Using the "550" Terminal

□ External Mass Storage Part 2 Digital and Audio Cas-
sette Systems

□Make Your 680b Smarter a cheap memory expander

□ Stop Bugs Now!

□Clocked Logic Part 1: The D Type and IK Flip-flops

□ The Cory Details of Cassette Storage

□ The Fun of Learning BASIC

□ Super-Tube jazzing up the Digital Croup TVT

April 1977

□ Interrupts Exposed . . using microprocessor interrupt
capability effectively

□Clocked Logic Part 2 Some Basic Applications

□ Build an Eight Channel Multiplexer for Your Scope

□Sorting Routines

□ Number Rounding Program

□ Meet the Tarbell/KC Interface

□ Super-Tester a digital design aid

□ The Hobbyist's Operating System Part 3 Command
Language Processing

□The Slow-Stepping Debugger

□ BASIC — The Easy Way

□Now You Can Use Software Timing Loops

□ KIM-1 Memory Expansion

□ Heavy Duty Power Supply

□ Digital Audio

□ HI-LO

□ Interfacing the Analog World

□ Everything about Semiconductor Memory

□ Three-State Logic . explanation of a key microprocessor
element

□Automatic Memory Dumper utility dump program for
6 800 users

□ Hangmath! a new puzzle/game

□Now — BASIC for the 8008 — Even'

□Microprogramming an insight into microprocessor de-
sign

□Computerized Babysitter

May 1977

□Clocked Logic Part 3. Data Converters and Special
Functions

□Cure Those End-of-Month Blues . with a sales analysis
program

□Make Your Investment Count the inside view of a
Custom MP-68

□ Speed Up Your 6800

□Who's Afraid of RS-232 . . data communications explained'

□is it High? — or Low?, understanding logic design con-
ventions

□Know Thyself! . confessions of a kit-builder

□ Protyping Systems Exposed ! ... a revealing look at the In-
tercept jr.

□ interrupts Exposed . . Part 2: Implementing an Interrupt-
driven System

□ Digital Audio . . . Part 2: Generating that Weird Music

□ Now It’s Imsai BASIC!

□ Bridging the Cap . tips on turning an application into a
program

□Adding "Plop" to Your System a noisemaker for com-
puter games

□ Lunar Lander

□Silence Noisy Teletype Motors Part 1: Getting the Ball
Rolling

□A Home Computer Pioneer profile of Don Tarbell

June 1977

□ Build Your Own Interface
□Computer Club Promotional Techniques
□Artillery Practice

□ Put a Micro in Your School

□ Torpedoes Away!

□ Build a Pulse Generator
□A TVT For Your KIM

□The BYTEDESTROYER review of an EPROM eraser

□ BASIC Timing Comparisons

□ Solving Keyboard Interface Problems
□A Clean Cassette

□ Try a Design Console . for practical hardware proto-
typing

□ Try Solar Energy

□ Simplified Billing System ... in BASIC for the small
business

□Kilobaud Klassroom . . No. 2: Cates and Flip-flops Ex-
plained

□Computerized Typesetting an introduction to word pro-
cessing

□ introducing! The World's Cheapest Computer a 56 0
SC/MP

□ My Friend is a Computer Junkie

July 1977

□ inside the Sphere Microcontroller

□ The Creat TV to CRT Monitor Conversion
□Computer Turns Director an interview with filmmaker

John Whitney

□The Random Number Came

□Cassette Interface First Aid . . . use your processor to set
timing

□ Understand Your Computer's Language

□ Kilobaud Klassroom. . No. 3: JK Flip-Flops and Clock
Logic

□Digital Audio Part 3: Signal Expansion and Compression
It Was Creat! . . . reviewing The First West Coast Computer
Fa ire

□ Pass the Buck . . . computer decision-maker program

□ inside the Amazing ASR 33 . . . checking out the most
popular terminal

□Try Computer Composition

August 1977

□Cassette I/O Format

□ Expand Your SWTP 6800 with a new 8K board
□Trigger Your Oscilloscope

□ Sobriety Tester Program

□ Random Integer Program
□Test ICs With Your Micro

□ Heavy Duty Altair Power Supply

□ Is the KIM-1 For Every-'i?

□Electronic Design by Computer

□Understand Your Computer's Language Part 2. Instruc-
tion Sets

kitfcxxd microcomputing

15 ISSUES FOR $15: A SUPER OFFER

August 1977, continued:

□ Enter the Audible Computer!

□Time Bomb Came

□ Try a Do-All Program!

□ Sooo, You Want to be an Author'

□SWTP 4K BASIC Notes implementing it on the 6 80b

□ Hexdec hexadecimal to decimal conversion

□ Start a One-Man Computer Club

□ Troubleshoot Your Software . a trace program for the
6502

□Cure that Hot Power Supply

September 1977

□ Build Your Own ASCII Keyboard with serial and
parallel output

□The Ultimate Personal Computer
□Talk Your Computer's Language'

□A PET For Every Home a look at the Commodore PET
2001

□ Kilobaud Klassroom No. 4 PC boards and power sup-
plies

□Seals Electronics

□ Try an 8080 Simulator

□ Build a $20 EPROM Programmer for the 5 402 4K chip

□ Faster MIKBUC Load Technique uses binary format
□Decoding Device Control Codes . uses a UART, naturally

□ Tarbell Asynchronous Format

□ Baseball in BASIC

□ Using an Invisible PROM how to relocate monitor pro-
grams

□ Klingon Capture Came
□Starting a Business?

October 1977

□ BASIC Timing Comparisons

□ Learn and Earn BASIC and business programming

□ Bargain Time!

□ Hello' Today's Program Is understanding computer
speech recognition

□ Beware the Altair Bus

□ Put Your Imsai on the Rack!

□ 3D Computer Craphics
□Memory Troubleshooting Techniques

□ Understand Your Interrupts' . real time clock appli-
cations

□ Kilobaud Klassroom No. .5 hardware logical functions

□ Digital Croup MAXI-Basic

□ Utilize ASCII Cpntrol Codes'

□ Dedicated Controllers

□ Try WORDMATH'

□Time for Timesharing?

□ Build a Universal I/O Board for your Altair

November 1977

□ Everything about Assemblers! . sure beats hand-coding
□Your Image Counts’

□Lifetime Program

□Consider a MITE Printer . . . alternative to theASR-33

□ Tired of Substituting Chips?

□ Stretch Those Characters mods for the SWTP PR-40

□ Magnetic Bubble Memory

□ Reliable Conversion Techniques
□Salesmanship. Hardware and Coffee

□ Hyper about Slow Load Times?. . KIM Hypertape is an
alternative

□ Interested in Commercial Programming?

□ Kilobaud Klassroom No. 6 voltage, current and power

supplies

□ Expand Your KIM! with Altair bus devices

□ Enhance Your Memory with home information retrieval

□ Build the $35 Modem . uses the MC14412 and a UART
□Another Look at Benchmark Program

□Son of Submarine Came

□ Payroll Program for small businessmen

□ SC/MP Coes Baudot add an inexpensive TTY

December 1977

□ TVT Hardware Design Part 1: instruction decoder and
scan

□ Expand Your KIM' . . Part 2 getting to the nuts and bolts

□ Payroll Program (Continued) cassette techniques
□The Business Market

□ALL CAPS

□The "Learning Machine" math tutor program

□ Kilobaud Klassroom No 7: transistors, diodes and op
amps

□Compleat Cuide to Logic Diagrams

□ Tiny BASIC

□The Twelve Days of Christmas

□ Paper Tape It's Here to Stay a look at the OP-BOA

□ Tempus Fugit
□Who Needs a Broker?

□ Here's HUEY! . . super calculator for the 65 02

□Crash Landing' a real-time Lunar Lander game
□File Structures Simplified

January 1978*

February 1978

□ Biorhythms with Your KIM

□ Vandenberg Data Products 16K Board Reviewed

□ inventory, Accounts and Reports

□ Small Business Software . . . Part 1: accounts receivable

□ The Music Man
□STAR WARS

U Hot-Rod Mods for Your SWTP System

□Tickled by Fickled a charting and diagramming aid

□ Ready on the Firing Line?

□ Expand Your KIM! . . . Part 3: bus control board and mem-
ory

□ interfacing Tips

□ Kilobaud Klassroom .No. 9: Counters and Registers

□ Teaching Preschoolers Letter Discrimination

□ Why Structured Programming?

□ Source Listing the Hard Way

□ How Good Is Tarbell's Floppy Interface?

□ Manipulating ASCII Data

□ Read any Good Books Lately? a program to test read-
ability

□George Morrow's Versatile Front-Panel Board

□ Deflection ! ... a video game for the quick and agile

□ How Much Memory for a KIM?

March 1978

□ Build the “Simple Computer" ... a home-brew 8080

□ Hardware Program Relocation, Part 2

□ State Capitals
□Customized MIKBUG

□ TV Typewriter Update

□ Foolproof Cassette Operation

□ Number-Crunching Time

□ Super Terminal! . . interfacing the Burroughs 9 350-2

□Consumer Computer, Inc.

□ Programmed Instruction Made Easy: Tiny PILOT, Part 1

□ Protect Your Memory Against Power Failure

□ Backup Techniques . . how fail-safe is your system?

□ Small Business Software, Part 2

□ Expand Your KIM! . . . Part 4: a TTY substitute

□ Faster Erase Times . build a quicker EPROM eraser

□ I/O Programming for the Altair Disks

□ The Axiom EX-800

□ Tiger Trouble! . . . Tl programmable-calculator safari

□ Temperature Sensing

□ A Different Approach to HI-LO

April 1978

□ Kilobaud's Mystery Program

□ Make Your Own PC Boards
nCP/M Primer

□Space-Saver System . . . the Tl 59 and PC-100A

□ How to Make Your SWTP System Happy

□ The Coming Tragedy: Poorly Designed Small-Business
Systems

□ Useful Programs for Your 6800

□ Memory Debugging

□ 3-D Tic-Tac-Toe

□ Programmed Instruction Made Easy: Tiny PILOT, Part 2

□ Blue Is the Color . . . Solid State Music is the company

□ Cash Register: A Practical Math Simulation

□ Parsing Techniques for the 6800

Ulncredizing . . . amazing, incredible game for 8080 sys-
tems!

□ Avoid Program Loading and Reloading
U Time-sharing for the Home System

□ Displaying Hexadecimal

□ Build a Touch-Response Display

□ Power-Down Mod for the TRS-80

□ Finally: 8080 Meets the Fairchild Video Game

□ Get a Watchdog ... to monitor those real-time operations

May 1978*

June 1978

□Taming the I/O Selectric . . . Part 1: hardware interface
n Home-Brew Z-80 System . . . Part 7. front-panel construc-
tion

□A Strategy for Healthy Living . computerized exer-
cise/fitness program

□ A Tour of the Faire, Part 1

□ Tiny BASIC Shortcuts

□ Baudot . . . er . . . Murray, Meet the H8

□ 8080, Z-80 or 8085

UOne Keyboard: Hex and ASCII

□ is the Malibu Model 160 the Printer for Your Business Sys-
tem?

□The Great Computer Conspiracy

^issues not available.

□ Personal Computer Shows
□Cross-Country Balloon Trip
□Transfer Vectors vs Absolute Addressing

□ Error Correcting Codes

□ ASCII to Baudot . . . er . . . Murray (the Hard Way)

□ Bowling Scores for Dollars

□ Machine Language for the TRS-80 ... Radio Shack's

T-BUC

□ Two Systems Sharing the Same Bus

□ Computers in Classrooms: Teaching the Teachers

July 1978*

August 1978

□ DOCUFORM: A Word-Processing System for Everyone!

□ Kilobaud Klassroom . . . No. 77: Data and Address Buses
1 (Software Debugging for Beginners

UMits vs North Star

□ Kansas City Standard ... at 1200 baud

□ Swords and Sorcery!

□ Two Hobbies: Model Railroading and Computing, Part 2
l J Update: Lunar Lander

□ The Do-It-Yourself System . . . Heath's H8 is a winner!

□ KIM -I- Chess — Microchess

□ is There Intelligent Life in Your Computer Room?

1 JFrom Base to Base . . with your HP 25

L 1FINANC: A Home/Small-Business Financial Package
l iComputer-Generated Signs

□ Copying Computer Cassettes

□ Something Extra With Radio Shack's BASIC

□ The Amazing 1802

□ Who Needs a UART?

□Can't Find It? . . . an index for your SWTP BASIC manual

September 1978

□(Con)text Editor

□ At Last: A Client Timekeeping System

□ Troubleshooters' Guide

□ Metric-American Conversion Program

□ The Heath/DEC Connection . . . Part 1: overview

□ Home System Demo Program

□ Do-lt-All Expansion Board for KIM

□ Tally Ho! ... fox and hounds game

□ Baudot Interface Cookbook

□ Error-Correcting Techniques

□ KIM Organ

□ Kilobaud Klassroom. . . No. 12: ROM and RAM mem-
ories

□ Motorola's Latest: The MC6802

□ TRS-80 Update: Level II BASIC

□ Super Cheap 2708 Programmer

□ Something Extra in Mass Storage . . . Meca's Alpha-1

□ From Big BASIC to Tiny BASIC

October 1978

□ Budget System . KIM, keyboard, TV, TVT-6L and AKIM

□ The Heath/DEC Connection . . . Part 2: H11 system periph-
erals

□ Depreciation Calculations

□ Looping in Tiny BASIC

□ Kilobaud Klassroom . . . No. 13: I/O Circuitry

□ Let Your Computer Wear a Watch

□ Randomness is Wonderful

□ Dazzler and BASIC

□ The Latest in Operating Systems for the 6800: FLEX
. Action on the Enterprise

□ Will DEC and IBM Be the Final Winners?

□ Little Bits

□ View from the Far East

□ Use That Parity Line!

□ The Software Patchcord

□ A Useful Address List Program
[ J Ready for the Nuthouse?

November 1978*

December 1978*

January 1979

□ An Editor for 6800 BASIC Programs

□ u-Panel for KIM

□ Rolling Dice

□ Pseudo Craphics

□ The BCS and Its President

□ Address List Editor

□ Display Your PET!

□ TRS-80 Tape Controller

□ SHHH — People Are Sleeping

□ Say It with a Banner

□ Open House

□ Cassette Interfacing

□ PET Techniques Explained

□ A Service Bureau for Hobbyists

□ Little Bits

□ Keeping Ma Bell Happy

kilobaud microcomputing

ARTICLES YOG MAY HAVE MISSED

February 1979

□ Block-Structured Language for Microcomputers
D Kilobaud Klassroom, No. 16: I/O IV

□ Computerized Climate Control

□ Music, Maestro!

□ Madam Dupre's House of the Zodiac

□ Disk Power!

□ Inventory Control with the TRS-80

□ Onward with the COSMAC Elf!

□ Build a $50 TVT!

□ Percom's LFLM00 Floppy Disk System

□ DOTS

□ The Apple Speaks— Softly

□ Super Mastermind

□ TRS-80 Level II Reference Manual Index

□ Care and Feeding of Cassette Tapes (Part 2)

□ Text/Document Preparation Made Easy

□ Simpler Interest

□ Leam BASIC— with BASIC

□ Use Flowcharts to Communicate

□ Joystick Interface for Your Altair

□ Attack on the Pack!

March 1979

□ Cheap Video for Your Heathkit H8

□ Analog and Digital Interfaces

□ The "El Cheapo" EPROM Programmer

□ Is Your Video Monitor Dangerous?

□ Thoughts on the SWTP Computer System

□ PET User Port Cookbook

□ Chess Pawn

□ Home Computer Exterior Ballistics

□ Heath H9 Page Erase

□ The SKIP II Microcomputer

□ Ultra Banner

□ Teletype's KSR-43

□ The One Percent Forecasting Method

□ Too Many Variables?

□ Kilobaud Klassroom No. 17: I/O V

□ The Electric Pencil

□ How to Talk to Your 8080

□ Programming the 1802

□ Keyboard Interrupt for the TRS-80

□ The OS I Model 500

□ Sleep Better with a Microcomputer

□ Telpar Thermal Printer

April 1979

□ A Look at TRS-60 Peripherals

□ Heath H8 Disk System

□ DOTS (Part 2)

□ Truly Random Numbers

□ SWTP CT-1024 Mod

□ Who Sells Software?

□ How Important Is Proper Termination?

□ How to Talk to Your 8080 (Part 2)

□ Parallel Port to RS-232 — Inexpensively

□ Free Speech Lessons for the TRS-80

□ Let's Co Flying

□ Floppy Disk System from Tarbell

□ The Wait State Explained

□ Depreciation Analysis

□ Twin Cassettes for Your TRS-80

□ Bar-Graph Generator

□ Let's Have Some Order

□ Quicksort!

□ Put Something Super in Your Life

□ Starship Attack

□ Terminate Your Troubles

□ Testing PET Search Algorithms

□ Two Diamonds

□ How about a Printer?

□ A Look inside the TRS-80

May 1979

□ A Text Formatter in BASIC

□ KIMCTR

□ High-Speed Cassette Interface

□ How to T alk to Your 8080 (Part 3)

□ Data Base Management

□ Analog and Digital Interfaces (Part 2)

□ COSMAC Double Play

□ COSMAC Double Play (cont.)

□ From Microcomputer to Micro-Piano

□ A Game of Darts

□ Prettyprinting with Microsoft BASIC

□ Kilobaud Klassroom No. 18

□ MDOS

□ A TRS-80 Cross-Index

□ Graphing with the TRS-80

□ An All-in-One Interface

June 1979

□ "Monitor"

□ TRS-80/Selectric Word Processor

□ Thoughts on the SWTP Computer System (2)

□ New Life for Our Altair

□ TVBUC

□ Creative Tabulation

□ A Handle on Programming

□ Keep book

□ Vector Graphing Techniques

□ Putting the 1802 on the S-100 Bus

□ A Personal Finance System (Part 1)

□ Building a New Horizon

□ Microcomputers and TVI

□ Translating Between TTL and RS-232 Levels

□ Data Files for Processor Tech 5K BASIC
U Little Bits

□ What's so Magic about the Sorcerer?

□ A Telephone Data Coupler for the TRS-80

□ The Cromemco Z-2D

□ Personal Computing, Meet Photography

□ Peripheral Interfacing

July 1979

□ 1C Logic Tester and Parallel I/O Expander

□ Whip file Wipeouts in the TRS-80

□ HUH Electronics' Model 8100 Motherboard

□ Data File Creation Program

□ Computer Careers in Carolina

□ Personal Finance System (Part 2)

□ Sargon Meets TRS-80

□ Safe I/O Ports with a Bidirectional Buffer

□ Projecting Future Profits

□ Randomness Is More Than It Seems

□ OSI's Superboard II

□ Teach an old PET New Tricks

□ A Circular Handle on Graphics

□ 1802 PILOT

□ Red-Handed Credit Grabber

□ Troubleshooting Tips and Techniques

□ Super Starter Kit from Technico

D Thoughts on the SWTP Computer System

□ CONOPS: an H8 Monitor

□ Getting the Most out of Your TRS-80

□ Reading Computer Jargon

□ An Introduction to Microfilming

□ The 6502 and Its Little Brothers

□ Another Hexadecimal Keyboard

August 1979

□ Cover Up: PET Home-Decorating Program
D Teleprinter Output for TRS-80

□ Murphy's Laws and Other Observations

□ Thoughts on the SWTP Computer System

□ MUSKBD: Music Program for the 6800

□ E-x-t-e-n-d Your Micro with the Mullen Extender Board

□ The BASIC BASIC Renumberer for H8

□ Shavasan Meditation Program

□ Personal Finance System (Part 3)

□ Percom CI-812 Mod

□ Report: Financial Reports Program

□ Haiku Composer: Poetry on the TRS-80

□ The Sorcerer Connection: Sorcerer to Teletype

□ Apple Ciphers: An Apple II Billing System

□ The PAIA 8700

□ Don't Throw Away That Monitor— Yet!

□ Nerves: A Fast Game

□ Taking AIM with Rockwell International's AIM 65

□ How to Silence a Noisy Computer

□ PET Wrap-up

□ Machine-Language Monitors for TRS-80

□ Visit to OSI

September 1979

□ A Look at Terminals

□ Inventory: Nine-operation Inventory Program

□ Metric. English Equivalents Program

□ A Look at Core Memory in Micros

□ The MM57109 Number Cruncher

□ Gas-Monitoring Program

□ The Fourth Faire

□ Output for the SWTP Editor-Assembler

□ Interfacing SOL with a Vista Disk

□ The Failure of a Micro in Business

□ Thoughts on the SWTP System

□ 2708 E PROM for the S-1 00

□ Review of Lear Siegler's ADM-3A

□ Off-the-Shelf Word-Processing System

□ Catching Bugs with Lights

□ Make PET Hard Copy Easy

□ Apple II High-Resolution Graphics

□ Beat the Computer: Blackjack Strategy

□ Put Your PET on the Betsi Bus

□ Build Your Own TTL Diagnostic Aid

□ Using and Expanding the Heath ET-3400

□ Another KIM-1 Expansion

□ Adult Caloric Requirements

□ TRS-80 Speed-up

October 1979

□ Thoughts on the SWTP Computer System

□ PAIA 8700 Revisited

□ Inexpensive TRS-80 Printer Interface

□ Eyes for the AC-30

□ Expanded TRS-80 Disk Operations

□ Anatomy of a Scam

□ Business Software Made Easy

□ KIMCTR Measures Capacitance

□ More TRS-80 Horsepower

□ Probos V: An Inexpensive Logic Probe

□ PET's Keyboard Grows Up

□ Hurricane! Track Hurricanes with This Program

□ Video DMA Interface for SWTP Systems

□ Ultimate Consumer Computer

□ The Exatron Stringy Floppy

□ Calendar Program

□ Four More Commands for SSB DOS

□ Arena: Go into Battle with Your Computer

□ File Directory Analysis for North Star DOS

□ Report on the Centronics 779 Printer

□ Beefing Up PET

□ AMI's EVK Series

□ Ulysses in Computerland

□ The Apple II Programmer's Aid ROM

□ Caps Lock, Not Shift Lock

□ Hardware Random Number Generator

□ Bit Rate Clocks for Your Serial Interface

□ Exploring the Inequality of Bus Buffers

□ Speed Up Your Elf's Input-Output

□ Load Programs the SIMPL Way

□ Pig Latin

□ Touch: This Icebreaker Could be a Jawbreaker

□ Program Debugging

□ Build an Inexpensive Logic Analyzer

□ Increasing the Bytesaver's Usefulness

November 1979

□ Lowercase for Your Apple II (Part 1)

□ What's New in Memory?

□ Stringy Floppy Encore

□ The Electronic Librarian

□ Text Editing for the TRS-80

□ The Apple Goes to Market

□ Let's Look at NEWDOS + from Apparat

□ AMI's EVK Series

□ Thoughts on the SWTP Computer System

□ Payroll Program for Business Systems

□ Thinker Toys' Discus I Disk System

□ Expanded TRS-80 Disk Operations

□ An SSM/Jade Video Board for Less Than $120

□ Wave the Flag

□ Real Property Profit Guide

□ The TRS-80 Dial-a-Phone

□ Wari: A Challenging Game

□ A-Mazing: Maze-Generating Algorithm

□ Sound for the Elf II

□ Sherlock Holmes and the Computer

□ ASCII-to-Selectric Software Driver

□ Introduction to Tl's TMS-9900

□ Have a Ball with Bally

□ The Output Buffer/Driver

□ Micropolis Disk Drives

□ Weight-Watching Special

□ $10 PET-to-Centronics Interface

□ A BASIC Dollar Edit $ubroutine

□ How to Build a Word Processor

□ Wire-Wrap Pin Locating

December 1979

□ Ithaca Intersystems' DPS-1

□ Electric Bill Watchdog

□ Lowercase for Your Apple II (Part 2)

□Simple Tracer for the 8080
□Chess I for Apple II
□"Sample" the Intersil/Harris 6100
□An Inexpensive and Easy EPROM Board

□ Eschew Obfuscation

□Message Display in Assembly Language

□ implementing an Algorithm
□$5 6800 Tape System
□AMI's EVK Series

□How to Choose a Small-Business Computer

□ Build a SISTER for Your 6800

□ Review of the S.D. Sales Expandoram

□ Peak Your TRS-80 Display
□Tiny Text Editor for the 1802
□The BASIC's of Computer Art

□ Reverse Video from OSI's 540 Board
□"Free" Computer Libraries

□ PET's Machine Language Monitor
□A Big Switch for the HI 7

□Converting Selectrlc Keyboards to Correspondence
Code

□ Extending the Altair Bus

□ H8 Alarm Clock Program

TM990/189 University Board

Is Texas Instruments’ TM990/189 a microprocessor’s microprocessor?

John Caulfield KOFUZ
2211 W. 119th Terrace
Leawood KS 66209

I don’t know how many other hobbyists
wait as long as I do to really get into
something, but my major contact with the
microcomputer world has been to read
about it and just be satisfied, in a vicarious
sort of way, with the fascination of the
microprocessor. I’ve always thought that
one of these days there’ll emerge a micro-
processor’s microprocessor that I’ll really
learn on, become a veritable genius at and
live happily ever after.

Texas Instruments’ TM990/189 University
Board comes closest to fitting my scenario.
Time will tell if it emerges as a micro-
processor’s microprocessor, but you pay
your money, you take your chances. Tl has
provided an approach that, for me, does it
all: alphanumeric keyboard, display,
monitor, assembler, audio cassette capa-
bility, EIA and TTY interface options, pro-
grammable I/O controller, addressable
LEDs, a squeaker speaker (piezoelectric
disk), matching power supply and a ver-
satile 16 bit CPU, the TMS 9980.

One of its biggest drawing cards is 570
pages of a self-paced tutorial text. My pre-
vious reading about this sport has made me
conscious of a checklist of features . . . Tl
seems to have packaged about all my

novice mind and budget could imagine into
its University Board.

Let’s look at the features of this 8 3/16 x
11 inch (20.8 cm x 27.9 cm) printed circuit
board, which is three-hole punched so you
can slip it into a three-ring binder.

The brains of the board is a TMS9980, the
microprocessor. This is a software-
compatible member of Tl’s 9900 family of
microprocessors. It is a single chip CPU
that has an 8 bit data bus, on-chip clock and
is a 40-pin device. Wait a minute, I can hear
you saying, I thought this was a 16 bit CPU.
Well, it is.

The TMS9980 has an external 8 bit data
bus, but internally it has a 16 bit data bus.
There’s an 8 bit latch right inside the 9980.
Each 8 bit data chunk that enters the 9980
via the external eight data bus pins is im-
mediately paired up with the preceding
eight bits. The combined 8 bit values form
the 16 bit internal word.

Monitor Program

The EPROM resident monitor, called
UNIBUG, enables you to communicate with
the TMS9980. The monitor program pro-
vides fifteen commands and seven
subroutines. The UNIBUG commands are
shown in Table 1.

in addition to the monitor commands,
there are seven utility subroutines that per-
form I/O functions. These subroutines are
called through the XOP (extended opera-
tion) assembly-language instruction. Table
2 shows these user-accessible utilities.

The monitor program has a roommate in-
side the 4K PROM, a two character sym-
bolic assembler. After entry of the A com-
mand from the keyboard, the monitor
passes program control to the resident
symbolic assembler. The assembler pro-
gram interprets assembly-language source
statements into object code. This saves you
the laborious, and often error-prone, task of
looking up hexadecimal op codes for any

70 Microcomputing January 1980

Input Results

A Assembler Execute

B Assembler Execute with current symbol table

C CRU Inspect/Change

D Dump memory to cassette

E Execute to breakpoint

F Status Register Inspect/Change

J Jump to EPROM

L Load memory from cassette

M Memory Inspect/Change

P Program Counter Inspect/Change

R Workspace register Inspect/Change
S Single Step

T “Typewriter" program

W Workspace pointer Inspect/Change
Ret New Line request

Table 1. UNIBUG commands.

one of the 69 instructions of the TMS9980,
plus formatting them for various address-
ing modes. The resident assembler will
save those of us in the microcomputer
novitiate anywhere from two to three light-
years of time and a like amount of de-
bugging frustration.

Just like the “big ole computers,” the
University Board assembler has several ver-
satile assembler directives (see Table 3).

Also, labels and comments can be used.
Labels may consist of one or two
characters— the first character must be
alphabetic; the second character may be
alphanumeric. Comments can be part of the
source statement and may include any
printable character.

Keyboard

So how do I, the lowly human, talk to this
fantastic monitor, symbolic assembler and
CPU? Simple, through the integral key-
board. Any breathing electronics jock
knows that Tl is in the calculator business.
Well, they very niftily took one of their
45-key keyboards and a ten digit seven-seg-
ment display and interfaced it to the Univer-
sity Board. The 45 keys operate in both a
shifted and unshifted mode. The keys are
shifted when you depress the SHIFT key; in
this mode, a shift LED is illuminated.

The keyboard display consists of ten
seven-segment LEDs. All of the letters of
the alphabet, numbers 0-9 and punctua-
tions .“#.;:,?! + - ()@/>%A*’$ = < are
available. How can all this be done with
seven segments?

Tl uses a stylized font— which means
that some of the letters and punctuations
will look rather strange at first (see Example
1, which demonstrates a v, K and M). You
may grow to prefer some of the stylized let-
ters and adapt them to your everyday life. In
fact, it will help keep your hobby just
esoteric enough so you can still “amaze
your friends.”

Although the display is ten digits, it is
capable of displaying any nine contiguous

characters of a maximum 64 character line.
The “shift display left” and “shift display
right” keys rotate the display six characters
at a time in a ring buffer to enable viewing
the 64 character line.

If you are an advanced enthusiast and
have an EIA or TTY terminal, you can
populate the EIA or TTY options on the
TM990/189. The printed circuit board is
predrilled and etched for the few needed
parts, and the User’s Guide details their in-
stallations.

v

SHOWS

UP

AS

U

K

SHOWS

UP

AS

H

M

SHOWS

UP

AS

Fi

Example 1.

Memory

Every microcomputer system, by defini-
tion, has memory. The TM990/189 comes

Schematic depiction of power supply.

Microcomputing January 1980 71

TM 990/1 89 User’s Guide.

with IK bytes of RAM expandable on-board
to 2K, and 4K bytes of PROM expandable
on-board to 6K. The 4K PROM contains the
UNIBUG Monitor and Symbolic Assembler.
The user can add either a 1 K x 8 or 2K x 8
EPROM in the expansion EPROM socket
provided.

For memory expansion beyond what is
on the board, all key address and data lines
are brought to a 40-pin connector where ad-
ditional memory may be interfaced. Tl pro-
vides a bus expansion interface on the
printed circuit board, which you populate to
interface to off-board memory. This option
will enable you to utilize the total memory
address capability of the TM9980 CPU, 16K
bytes.

The University Board may be interfaced
to an audio cassette for mass program
storage. The User’s Guide gives the connec-
tion details and parts required. To accom-
plish this, again, the printed circuit board
has the etches, but the user supplies the
parts— a relay and a transient protection
diode.

Ever since I first started reading about
microprocessors, I’ve wondered about I/O,
or, how can I get this circuit to actually do
something? The University Board has two
main vehicles to the outside workaday
world. First, there is memory-mapped I/O
that treats I/O as a memory location.
Almost all microcomputer systems have

XOP# Function

8 Write one hexadecimal character to the
terminal

9 Read hexadecimal word from the terminal

10 Write four hex characters to the terminal

1 1 Echo character

12 Write one character to the terminal

13 Read one character from the terminal

14 Write a message to the terminal

Table 2. Utility subroutines.

this capability; the TMS9980 CPU is no
exception.

CRU Interface

The second I/O vehicle is the com-
munications register unit, or CRU. The CRU
is a definite distinguishing factor of Tl’s
TMS9900 family. It provides for a serial
transfer of one or more bits in or out of the
CPU via two dedicated pins on the
9980— CRUIN and CRUOUT. A clock,
CRUCLK, is used as a time strobe to coor-
dinate data transfers. Use of the CRU does
not subtract from any available memory
locations, and it is separate from the data
bus.

The major advantage of the CRU is “bit
diddling.” A single bit (or multiple bits up to
16) may be changed in the CRU output
scheme. A single bit is all that is necessary
to monitor or change the status of a motor,
relay, switch, etc., i.e., the outside world.

There are five instructions that program
the CRU interface:

LDCR— Enables the user to load from
memory a pattern of 1 to 16 bits and serially
transmit this pattern through the CRUOUT
pin.

STCR— Enables the user to store into
memory a pattern of 1 to 16 bits obtained
serially at the CRUIN pin.

SBO— Sends a “logical one” through the
CRUOUT pin.

SBZ— Sends a “logical zero” through the
CRUOUT pin.

TB— Tests the value at the CRUIN pin and
reflects the test results in the equal bit of
the Status Register.

The last three instructions, SBO, SBZ and
TB, are the real aids to the control applica-
tions. They enable you to turn on and off
loads as well as check their status. The
CRU becomes a fascinating concept
beyond the typical memory-mapped I/O sys-
tems.

Power Requirements

The nominal power requirement with the
on-board memory options fully populated is
+ 5 V @700 mA, +12V @100 mA and -12
V @16 mA. Luckily for me, Tl supplies a
matching fossil-fuel-fired power plant, the
TM990/519, to supply the required “juice.” If
you start adding off-board options, you’ll

Inputs Functions

AORG Absolute origin of the statement

BSS Block of memory reserved with starting
symbol

DATA Sixteen bits of immediate value
END End of program, exit to monitor, load
program counter

EQU Symbol equated to value in operand

TEXT String of ASCII coded characters

Table 3. Symbolic assembler.

soon run out of power supply. So keep your
power budget in mind with respect to the
TM990/519’s capabilities.

Documentation

A major ingredient of the TM990/189
University Board package is the tutorial
text, entitled Introduction to Micropro-
cessors— Hardware and Software. This 500
plus page document stepped me through
every inch of the system. It makes liberal
use of illustrations, understandable and
practical examples, and it is directly keyed
to the TM 990/1 89 for immediate hands-on
reinforcement. (I especially enjoyed the il-
lustration that built up to a Morse code
translator. With a little bit of tweaking I’ll be
able to use it with my ham radio!)

The text is simple enough for the relative
novice to use, but the book’s authors
(George Goode and Associates, Dallas,
Texas) point out that the book can also be
used as the central text in an introductory
three-hour college course on microcom-
puter systems. The chapter titles are:

1 . Overview of Computers, Microprocessors
and Microcomputers

2. Arithmetic, Logic and the ALU

3. Introduction to Computer Addressing
and Program Development

4. Assembly Language

5. Memory Systems

6. Input/Output Concepts

7. Input/Output Design

8. Modular Programming

9. Software Engineering

10. Product Development

In addition to the tutorial text, Tl supplies
a well-written 150 page user’s guide. The
documentation is of professional quality
and highly readable.

The assembled board (no kits), tutorial
text and User’s Guide is $299. The tutorial
text alone is $19.95; User’s Guide , $5.95;
TM 990/5 19 power supply, $65. ■

TM990/189 tutorial text.

72 Microcomputing January 1980

With these disks, I can turn your
TRS-80 into a serious computer.

I'm Irwin Taranto, and I've put the first com-
puter into more than 300 different businesses.

It’s taught me that the TRS-80 is an
elegant piece of hardware despite its low
price. Given the right programs, it can jump
through hoops.

Put simply, I have the right programs. Four
of them are the genuine Osborne & Associates
systems, originally designed for the $30,000
Wang computer. I’ve made a few minor modifi-

THE OSBORNE PROGRAMS

Accounts Payable: invoice-linked, it reports,
does checks and links to general ledger.
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General Ledger: handles 1750 transactions each
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Payroll: figures the pay, does the checks and all
the bookkeeping.

AND MY OWN PROGRAMS

Inventory Control: gives immediate readout on
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NEW! Invoicing: linked to accounts receivable.
Prints invoices and feeds data into receivables.

cations, and they now work on a $4000 TRS-80.
The other two programs I added myself.

These programs are fully- documented,
and you can buy the books locally or from me.

I made them work on the TRS-80, and if you buy
them from me, I’ll make them work for you.

If you’re not sure about that, call the
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the people who’ve bought all over the world.
Then ask them.

These programs cost $99.95 each. (The
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the instructions you need and my phone num-
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If your question’s tough enough, I’ll talk to
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Because I plan to turn that TRS-80 of yours
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& ASSOCIATES

P.O. Box 6073, 4136 Redwood Highway, San Rafael CA
94903 • (415) 472-1415. Add $3 per order for handling,
6% sales tax in California only. If you don’t already
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Mastercharge, Visa OK.

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Send my free Heathkit Catalog now.
I am not currently receiving your
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i/ 0 Reader Service— see page 227

Microcomputing January 1980 73

A Not-So-Fast Renumberer
for OSI BASIC

Written in BASIC, this utility makes your listings neat and tidy.

John W. Aug hey
27384 Lamplighter Lane
Elkhart IN 46514

T his article describes a
routine that will renumber
BASIC programs for the Ohio
Scientific BASIC-in-ROM com-
puters. The program itself is
written in BASIC and was
designed, on and for my per-
sonal machine, a Challenger
C2-4P. However, it has also been
tested and found to work with-
out modification on the Chal-
lenger C1-P and C2-8P ma-
chines. Hence, any OSI com-
puter with BASIC-in-ROM can
make use of this renumbering
routine. I would like to thank Phil
Thornton of Elkhart Computer
for providing a Challenger C1-P
on which to test the program.

I decided to design this pro-
gram and write this article for
three major reasons. First, I
have been the proud owner of
my C2-4P for a number of
months now and, as a result,
have written a sizable library of
BASIC programs that I would
like to tidy up and expand.
Second, I hope to make a few
bucks from publishing this arti-
cle so I can buy more hardware
to write more programs that will
need to be renumbered. And
finally, in a February 1979 letter
to the editor (p. 20), E. Morris of
Midland, Michigan, said he
would not renew his subscrip-
tion unless there was an article
oreinted toward us Ohio Scien-
tific users in the next eleven
months. I’m always glad to keep
a fellow OSI user happy.

After having used their
machines for a reasonable
period of time, most OSI users
would agree that one significant
feature absent from the OSI ver-

sion of Microsoft BASIC-in-ROM
is the ability to renumber an ex-
isting program. This is a short-
coming that, until recently, I had
managed to circumvent manual-
ly by writing programs with large
gaps in the statement numbers
and renumbering manually from
printed listings when the source
got too shabby to share with
fellow programmers. However,
my professionalism (I program
operating system software for
an Amdahl 470/V5 to support my
hobby and family) got to me
recently, and I finally decided
that if I can renumber by hand,
then I should certainly be able to
tell the 6502 how to do it by
itself.

In the process of collecting
ideas for an OSI renumber
routine, I read a number of ar-
ticles by others who have writ-
ten renumber routines for other
systems— some in machine
code and others in BASIC, some
for 6502 machines and some
not. The common foundation for
all of these routines is a
knowledge of how the BASIC in-
terpreter stores the user’s pro-
gram in memory for execution,
and I knew this was the key to
designing a renumber routine
for OSI’s version of BASIC.

OSI’s BASIC-in-ROM stores a
user’s source program starting
at decimal location 769 in RAM.
Each statement is composed of
a four-byte header, followed by
the compressed statement and
terminated with a single byte of
zeros. The four-byte header
contains two 2-byte data words.
The first word is the address of
the next sequential statement,
or zeros if this is the last state-
ment in the program. The
second word contains the state-
ment number in binary format.

Routine Design

My first attempt at writing a
renumber program was de-
signed to renumber only the
statements themselves, with no
consideration of renumbering
GOTOs, GOSUBs, THENs or
RUNs embedded in the text of
the statements. This was a
relatively simple task that in-
volved chaining from one state-
ment to the next and inserting
the new binary statement
number into the second data
word in the header I mentioned
before.

The crux of this simple-
minded renumberer is con-
tained in lines 32000-32010 of
the final version (see the listing).
This first attempt at renum-
bering proved quite useful, but it
was still a nuisance to have to
go back and manually renumber
the GOTOs, etc.

The tricky part comes when
you go back and attempt to
renumber the internals of the
statements. As others who have
written renumber routines have
found, there is an inconsistency
in the way statement numbers
are stored. The numbers on the
statements themselves are in
binary form, but the statement
number references in GOTOs,
etc., are in ASCII.

Fortunately, the OSI BASIC
has the very useful STR$ and
ASC functions to aid in the con-
version process from binary to
ASCII. Luckily, the conversion in
the other direction— from ASCII
to binary— is not too difficult to
perform in BASIC without sup-
port functions.

The OSI BASIC, as do most
others, uses “tokens” to allow
the compression of the BASIC
source into a smaller package in

memory. The tokens are simply
single-byte flags with values in
the range of decimal 128-255,
beyond the range of valid ASCII
codes, which are used to take
the place of the BASIC com-
mand verbs.

Whenever the BASIC scanner
finds a string of characters it
recognizes as a keyword, such
as GOTO, it replaces that
character string with the single-
byte token that corresponds to
that keyword. The renumber
routine must thus scan for the
tokens requiring renumbering
and alter the statement num-
bers that follow them. In the OSI
version of Microsoft BASIC, the
tokens we need to look for are
decimal 136 (GOTO), 137 (RUN),
140 (GOSUB) and 160 (THEN).

The renumber routine is
organized into two parts. The
first part is the “simpleminded”
renumberer I described earlier,
with one additional function.
While it is inserting the new
statement numbers, it also must
save the old statement numbers
in a chunk of RAM so the second
pass will know how to renumber
the internals of the statements.
In OSI systems with video
boards, one of the most conve-
nient chunks of RAM is the
video display memory, which
begins at 53248 decimal. Each
statement number saved uses
two bytes, and two bytes are re-
quired for an end-of-table flag.
Hence in the C1-P machines
with 1024 bytes of video RAM,
you can renumber a program
with as many as 51 1 statements.
In the C2-4P you can handle
1023 statements with its 2K of
video RAM.

The second part of the
renumberer goes back and
looks at the text in the state-

74 Microcomputing January 1980

□

®

□

□

□

□

□

©

®

□

0

®

□

©

□

©

®

□

I

□

©

□

©

□

©

□

©

□

©

□

©

□

©

□

©

TRS-80 MODEL II FORMAT NOW AVAILABLE

DIGITAL RESEARCH m JZ/7ST

CP/M* FLOPPY DISKETTE OPERATING SYS-
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$145 525

CP/M version 2 (not all formats available immediately)
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MAC — 8080 Macro Assembler. Full Intel macro defini-
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(seebelpw) $100/$15

SID — 8080 symbolic debugger. Full trace, pass count
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TEX — Text formatter to create paginated, page-num-
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BASIC COMPILER — Language compatible with
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Software /

with / Manual
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tended precision variables, etc $109 $15

STRUCTURED SYSTEMS GROUP

□ GENERAL LEDGER — Interactive and flexible sys-
tem providing proof and report outputs. Customization of
COA created interactively. Multiple branch accounting
centers. Extensive checking performed at data entry for

sary. Requires CBASIC $899 $25

□ ACCOUNTS RECEIVABLE - Open item system

with output for internal aged reports and customer-ori-
ented statement and billing purposes. On-Line Enquiry
permits information for Customer Service and Credit de-
partments. Interface to General Ledger provided if both
systems used. Requires CBASIC $699 $25

□ ACCOUNTS PAYABLE - Provides aged state-
ments of accounts by vendor with check writing for
selected invoices. Can be used alone or with General
Ledger and/or with NAD. Requires CBASIC $699/$25

□ LETTERIGHT — Program to create, edit and type let-

ters or other documents. Has facilities to enter, display,
delete and move text, with good video screen presenta-
tion. Designed to integrate with NAD for form letter mail-
ings. Requires CBASIC $1 79 $25

□ NAD Name and Address selection system — interactive

mail list creation anp maintenance program with output
as full reports with reference data or restricted informa-
tion for mail labels. Transfer system for extraction and
transfer of selected records to create new files. Requires
CBASIC $79/520

□ QSORT — Fast sort/merge program for files with fixed

record length, variable field length information. Up to five
ascending or descending keys. Full back-up of input files
created $95/ $20

GRAHAM-DORIAN SOFTWARE
SYSTEMS

□ PAYROLL SYSTEM — Maintains employee master

© file. Computes payroll withholding for FICA, Federal and
(g> State taxes. Prints payroll register, checks, quarterly re-
ports and W-2 forms. Can generate ad hoc reports and
employee form letters with mail labels. Requires
CBASIC. Supplied in source code $590/535

□ APARTMENT MANAGEMENT SYSTEM - Fi-

© nancial management system for receipts and security
<g) deposits ol apartment projects. Captures data on vacan-
cies, revenues, etc. for annual trend analysis. Daily report
shows late rents, vacancy notices, vacancies, income
lost through vacancies, etc. Requires CBASIC. Supplied
in source code $590/535

□ INVENTORY SYSTEM - Captures stock levels,
© costs, sources, sales, ages, turnover, markup, etc.
<g) Transaction information may be entered for reporting by

salesman, type of sale, date of sale, etc. Reports avail-
able both for accounting and decision making. Requires

CBASIC. Supplied in source code $590 $35

G CASH REGISTER — Maintains files on daily sales.
© Files data by sales person and item. Tracks sales, over-
<g> rings, refunds, payouts and total net deposits. Requires
CBASIC. Supplied in source code $590/535

□ tiny C — Interactive interpretive system for teaching

structured programming techniques. Manual includes full
source listings $75 $40

□ BDS C COMPILER — Supports most major features
® of language, including Structures. Arrays, Pointers,

recursive function evaluation, linkable with library to 8080
binary output. Lacks data initialization, long & float type
and static & register class specifiers. Documentation in-
cludes "C" Programming Language book by Kernighan &
Ritchie $110/515

□ WHITESMITHS’ C COMPILER - The ultimate in
© systems software tools. Produces faster code than Pas-
cal with more extensive facilities. Conforms to the full
UNIX*** Version 7 C language, described by Kernighan
and Ritchie, and makes available over 75 functions for
performing I/O, string manipulation and storage alloca-
tion. Compiler output in A-Natural source. Supplied with
A-Natural (see below) requires 60K CP/M $630/$30

□ A-NATURAL — Narrative assembler with linking load-
© er, librarian, extensive 8080 subroutine library in A-

Natural relocatable format and translators from A-Natural
source to Microsoft MACRO-80 source and from A-
Natural rel to source $330 $1 5

Software for most popular 8080/Z80 computer disk systems including

and formats.

Tl *The Software Supermarket is a trademark of Lifeboat Associates

scrolling, interactive search and replace, automatic text
wrap around for word processing, operations for manipu-
lating blocks of text, and comprehensive 70 page manual.

$135/515

□ POLYTEXT/ 80 — Text formatter for word processing
® applications. Justifies and paginates source text files. Will
generate form letters with custom fields and conditional
processing. Support for Daisey Wheel printers includes
variable pitch justification and motion optimization.
$85/515

□ ALGOL-60 — Powerful block-structured language

® compiler featuring economical run time dynamic alloca-
tion of memory. Very compact (24K total RAM) system
implementing almost all Algol 60 report features plus
many powerful extensions including string handling direct
disk address I/O etc. Requires Z80 CPU $199/520

□ Z80 DEVELOPMENT PACKAGE - Consists of:

<8> (1) disk file line editor, with global inter and intra-line facili-
ties; (2) Z80 relocating assembler. Zilog/Mostek mne-
monics, conditional assembly and cross reference table
capabilities; (3) linking loader producing absolute Intel
hex disk file $95 $20

□ ZDT — Z80 Debugger to trace, break and examine reg-

® isters with standard Zilog/Mostek mnemonic disassem-
bly displays. $35 when ordered with Z80 Development
Package $50/$ 10

G DISTEL — Disk based disassembler to Intel 8080 or
TDL/Xitan Z80 source code, listing and cross reference
files. Intel or TDL/Xitan pseudo ops optional. Runs on

8080 $65/510

Q DISILOG — As DISTEL to Zilog Mostek mnemonic
® files. Runs on Z80 only $65/510

Q TEXTWRITER III — Text formatter to justify and pagi-
® nate letters and other documents. Special features in-
clude insertion of text during execution from other disk
files or console, permitting recipe documents to be
created from linked fragments on other files. Has facilities
for sorted index, table of contents and footnote insertions.

Ideal for contracts, manuals, etc $125/520

_] POSTMASTER — A comprehensive package for mail
® list maintenance. Features include keyed record extrac-
tion and label production. A form letter program is in-
cluded which provides neat letters on single sheet or con-
tinuous forms. Requires CBASIC $1 50/525

G WHATSIT?**** Interactive data-base system using
associative tags to retrieve information by subject. Hash-
ing and random access used for fast response. Requires

CBASIC $125/525

G XYBASIC Interactive Process Control BASIC — Full
disk BASIC features plus unique commands to handle
bytes, rotate and shift, and to test and set bits. Available
in Integer, Extended and ROMable versions.

Integer Disk or Integer ROMable $295 525

Extended Disk or Extended ROMable $395/525

Q SMAL/80 Structured Macro Assembled Language —
Package of powerful general purpose text macro proc-
essor and SMAL structured language compiler. SMAL is
an assembler language with IF-THEN-tLSE. LOOP-
REPEAT-WHILE. DO-END, BEGIN-END constructs

$75/515

Q SELECTOR III-C2 — Data Base Processor to create
® and maintain multi Key data bases. Prints formatted,
sorted reports with numerical summaries or mailing
labels. Comes with sample applications including Sales
Activity. Inventory, Payables. Receivables, Check Regis-
ter, and Client/Patient Appointments, etc. Requires
CBASIC Version 2. Supplied in source code $345/520
G CPM/374X — Has full range of functions to create or
re-name an IBM 3741 volume, display directory infor-
mation and edit the data set contents. Provides full file
transfer facilities between 3741 volume data sets and
CP/M files $195/510

G BASIC UTILITY DISK — Consists of: (1) CRUNCH-
® 14 - Compacting utility to reduce the size and increase
the speed of programs in Microsoft Basic and TRS-80
Basic. (2) DPFUN - Double precision subroutines for
computing nineteen transcendental functions including
square root, natural log, log base 10, sin, arc sin. hyper-
bolic sin, hyperbolic arc sin, etc. Furnished in source on

diskette and documentation $50/535

G THE STRING BIT — Fortran character stnng han-
® dling. Routines to find, fill, pack, move, separate, con-
catenate and compare character strings. This package
completely eliminates the problems associated with
character string handling in FORTRAN. Supplied with
source $45 $15

S BSTAM — Utility to link one computer to another also
equipped with BSTAM. Allows file transfers at full data
speed (no conversion to hex), with CRC block control
check for very reliable error detection and automatic re-
try. We use it! It's great! Full wildcard expansions to
send *.ASM, etc. 9600 baud with wire, 300 baud with
phone connection. Both ends need one. Standard and M
versions can talk to one another $1 50/55

G Flippy Disk Kit — Template and instructions to modify
single sided 5 ’A" diskettes for use of second side in sin-
gled sided drives $12.50

‘CP/M is a trademark of Digital Research
"280 is a trademark of Zilog. Inc.

•"UNIX is a trademark of Bell Laboratories
""WHATSIT? is a trademark ol Computer Headware

fCP/M lor Heath. TRS-80 Model I and PolyMorphic 8813 are
modified and must use specially compiled versions of system
and applications software

® Modified version available for use with CP/M as implemented
on Heath and TRS-80 Model I computors

©User license agreement for this product must be signed and
returned to Lifeboat Associates before shipment may be made

Orders must specify disk
systems and formats
e g North Star single,
double or quad density.
IBM single or 2D/256.
Altair. Helios II.
Micropolis Mod I or II,
5%" soft sector (Micro
■COM SO Systems
Dynabyte). etc
Prices F O B New York
Shipping, handling and
C.O.D. charges extra
Manual cost applicable
against puce ol
subsequent software
purchase
The sale of each
propriety software
package conveys a
license for use on one
system only

Lifeboat Associates, 2248 Broadway, n.y„ n.y. 10024

(212) 580-0082 Telex : 668585

ments, looking for the four
tokens noted earlier. When it
finds one of them, it looks
behind it to see if there is a
statement number. If the routine
finds a statement number 1, it
converts it from ASCII to binary
and then compares it against
the statement numbers that the
first pass saved in the video
RAM.

At this point one of two things
can happen to the renumber pro-
gram. The first is that it finds the
old statement number in the
table. If this occurs all is OK,
and we proceed normally. The
alternative is that the routine
can’t find the old statement
number, in which case there
was an error in your original
source program, such as a
GOTO with a missing destina-
tion.

Improvisations

But at this point your old pro-
gram is partially renumbered,
and we can’t just stop renum-
bering. So to recover, I chose to
insert percent signs (%) where
the missing statement number
was, to indicate in the renum-
bered listing that something
went wrong during renum-
bering. It would have been nice
to print an error message at this
point, but doing so would have
disturbed the video RAM where
the old statement numbers were
stored. I discovered this the
hard way after much head
scratching!

If the program successfully
found the old statement number
in the video RAM, it must now in-
sert the corresponding new
statement number in the BASIC
text in place of the old number.
Here is where the STR$ and ASC
functions of BASIC come in to
play. One minor quirk that must
be addressed here is that the
STR$ function returns a leading
blank in the character string,
probably where a sign would
go, and this blank should be
skipped over when POKEing
back the ASCII characters.

At this point we run into
another possible error condi-
tion. What happens if the new
statement number has more
digits than the original state-
ment number and, hence, won’t
fit over top of it? Again, I chose

to overlay the old statement
number with a special charac-
ter, in this case the ampersand
(&), to flag the error and distin-
guish this type of error from the
“old statement not found” con-
dition noted before.

A few other minor changes

are required to make this renum-
bering technique work. Most im-
portant is to make sure that the
program doing the renumbering
does not try to renumber itself.
Strange and undesirable things
can happen if a program at-
tempts to dynamically re-
number itself. To prevent this
from occurring, the renumber
program checks for statement
numbers greater than 31998 and

leaves them alone. Since the
renumberer starts at statement
31999, it will remain intact.

Operation

The procedure to use the
renumber program is relatively
simple. First, load in the

renumber program, which starts
at statement 31999. Actually,
the first executable statement is
at 32000; the END at 31999 is in-
serted to stop a user program
that terminates by falling
through to the end of the pro-
gram without an explicit END
statement. After loading in the
renumbering program, load or
key in the program you wish to
renumber. It is assumed that

this program will not have state-
ment numbers greater than
31998.

After loading is complete, key
in RUN 32000 to begin renum-
bering. You will be prompted for
the desired beginning new
statement number and incre-
ment value. After this, the only
visible evidence that renumber-
ing is in process is that some ap-
parently meaningless charac-
ters will appear at the top por-
tion of your video monitor during
the first renumbering pass:
These are the old statement
numbers being saved in the
video RAM. These may not be
visible if you are renumbering a
short program on a Cl -P system,
due to video overscan.

After this there will be a
relatively long pause, possibly
several minutes, depending on
the size of the program being
renumbered. Be patient; do not
press control-C or BREAK
during this period or the pro-
gram being renumbered will be
left only partially renumbered,
since the video RAM will be
disturbed. When renumbering is
completed, BASIC will prompt
you with an OK, and you can pro-
ceed to list and save your
renumbered program. To save or
list just your renumbered pro-
gram and not the renumbering
code, key in LIST 1-31998, and
any statements in your program
will be listed.

The renumberer can be a
valuable tool during program
development by allowing dyna-
mic renumbering while you are
in the process of coding and
testing a new program. It gives
the added benefit of checking
for missing destinations on
GOTOs and GOSUBs that might
otherwise go undetected until
an unusual condition arose in
program execution.

The renumberer does not af-
fect the execution of the user
program while coexisting with it
in the machine, other than by oc-
cupying memory that would
otherwise be available for vari-
ables. The program statements
for the renumberer occupy just
under IK bytes, and the require-
ment for variables during execu-
tion will bring the storage re-
quirement up somewhat beyond
that.B

31999

END

32000

CLEAR: PR I NT "START AND INC" : INPUTNF * IN

32001

AD=769 : SS=53248 : SN=NF

32002

SL=PEEK <RH+2> : SH=PEEK <RD+3>

32003

PE3KESS » SL 8 POKESS+ 1 * SH: SS=SS+2

32004

□S=SL+256*SH

32005

I FE3S <3 1 999THEN32 0 07

32006

PDKESS > 255 : PDKESS+ 1 ? 255 : GDTD32 0 1 1

32007

BT= I NT <SN/256> : PDKEAD+3 * BT

32008

BT=SN-256^BT : PDKEAD+2* BT

32009

AD=PEEK (AID +256*PEEK (AD+l) : SN=SN+IN

32010

IFADO 0THEN32002

32011

RD=769 : MN=SN : SN=NF

32012

BP=RD+4

32013

BT=PEEK. CBP>

32014

I FBT = 0THEN32 02 0

32015

I FBT= 1 36THEN32 023

32016

I FBT= 1 37THEN32 023

32017

I FBT=1 40THEN32023

32018

I FBT= 1 6 0THEN32 023

32019

BP=BP+1 : GDTD32013

3202 0

RD=PEEK <RD> +256+PEEK <AD+1> : SN=SN+IN

32021

I FSN CMNTHEN32 0 1 2

32022

END

32023

BP=BP+1 : BT =PEEK <BP>

32024

I FBT= 0THEN32 02 0

32025

I FBT =32THEN32 023

32026

IFBT=44THEN32023

32027

I FBT C48THEN32 014

32028

I FBT> 57THEN32 014

32029

FC=BP: LC=BP: DS=BT-48

32030

BP=BP+1 : BT=PEEK <BP)

32031

I FBT <48THEN32 034

32032

IFBT>57THEN32034

32033

□S=DS^1 0+BT-48: LC=BP: GDTD3203Q

32034

SS=53248: JS=NF

32035

I =PEEK <SS> +256+PEEK: <SS+ 1 >

32036

I FJS> =MNTHEN32 039

32037

I F I =0STHEN32 042

32038

SS=SS+2: JS=JS+IN: GDTD32035

32039

JS=37

32040

FDRI=FCTDLC: PDKEI ? JS: NEXT I

32041

GDTD32024

32042

AS-STRS CJS> : I=LENCA$>

32043

I F I > LC-FC+2THEN JS=38 : GBTD32 04 0

32044

FDRI=FCTOLC: PDKEI j. 32: NEXTI

32045

LC=FC+LEN <R$> -2

32046

FDRI=FCTOLC

32047

JS=ASC<:MIDS(R$> I-FC+2* 1>>

32048

PDKEI 9 JS: NEXTI

32049

GDTD32024

Program listing.

76 Microcomputing January 1980

Outpost Tl has OEM

’s Outpost 1 1
is a highly flexible, easily adaptable
microcomputer capable of handling virtually any control,
communications, or stand-alone small business computing application.
Two points make it the outstanding choice for incorporation into OEM systems:
Cost. TANO’s high-volume production means Outpost 1 1 is available at
a most attractive price, with multi-unit discounts.

Reliability. Modular design using
military/industrial grade components yields 6060-hour MTBF. performance.

Add to that the finest software tools and a variety of interface options
(serial line, parallel, digital acquisition or analog acquisition) and you have
the most versatile microcomputer in its price range.

If you’re an OEM, Outpost 1 1 has your name written all over it.

See your nearest TANO representative and get it into your system.

TANO Corporation, 4301 PocheCourt West, New Orleans, La. 70129, (504) 254-3500.

written all over it. Get
into your system.

it

Visions of

Sacks of Silver Dollars

Teach ’em a thing or two at the casinos with this Blackjack-strategy tutor.

Thomas W. Glaser
RR 1

Rochester MN 55901

A h . . . Vegas and the glitter-
ing casinos filled with row
after row of green-felt tables
manned by the ever-efficient
dealers of Twenty-one gently
riffling card decks as they pre-
pare the “shoe.” Does there ex-
ist a would-be gambler who has
not dreamed of making a killing
at one of these tables and de-
parting Las Vegas with a bag of
some casino’s loot?

I had such dreams prior to my
first trip to Vegas last year. To
enhance my chances for suc-
cess I looked for ways to sharp-
en my skills before the big test,
as I’m sure others do. I visited
the local bookstore and found
several books and pamphlets
describing various methods of
successfully playing these
mystical games of chance for
profit.

I purchased one of these
sources of winning strategy for
the game of Blackjack and, for
the following several evenings,
practiced as best I could mak-
ing the correct strategic
choices from many sample
hands. Though the way I prac-
ticed didn’t seem very efficient,

I at least managed to leave
Vegas with slightly more green-
backs than I had arrived with
(though nothing resembling a
bag was needed to carry away
my loot).

Recently I was reminded once
again of this need for each of

us to polish our skills prior to
our try at the real thing, and the
ideal practice method came
clearly into focus. The idea for
a computerized Blackjack tutor
was born when my friend Ted
strolled into my classroom one
morning with that gambler’s
glint in his eyes. In his hands
was a copy of the Rules of
Blackjack and an airline ticket
to sunny Nevada some four
weeks hence.

Now, Ted is a sly fellow in his
own way. He knows of my near
fanatical interest in microcom-
puters and has a good appre-
ciation of their capabilities. So
he had come with a not-so-inno-
cent question in mind: “How
difficult would it be to create a
Blackjack teacher that would
deal random hands and then
check my ability to make the
correct choice?”

Some ideas rather easily

DEALER'S UP CARD
3456789 10 A

Fig. 1. Basjc Blackjack strategy.

arouse my interest, and I had
the distinct feeling that Ted
knew this idea would fit that
category. I had played different
versions of Blackjack dn sever-
al systems, but never one that
had provided feedback on cor-
rect strategy. If I had only had
such a tireless gambling tutor
before my venture to Vegas . . .
mmm . . . visions of sacks of
silver dollars.

Bouyed by the Idea that
others (especially Microcom-
puting readers) might also ben-
efit from such a teacher, I told
Ted his tutor would be ready for
some serious practice ses-
sions before his scheduled
flight to the Strip.

Blackjack Strategy

There are countless books
that describe the rules and ba-
sic stategy of the game of
Blackjack, or Twenty-one. The
object of the game is, of course,
for the player to hold a hand
that has a count not greater
than 21, but greater than the
count held by the dealer. It is
perhaps the only casino game
in which the player exercises
judgement and discretion in
the play of the cards. Thus, the
player’s chances of success
can be improved considerably
by increased knowledge of
probabilities and correct strat-
egy.

There are several techniques
the player can learn to enhance
his playing ability. Some, like
counting, are too complicated
and require too much practice
and concentration for the casu-
al player. The strategy taught

by the tutor is condensed from
several sources and consists of
these simple rules:

1. When the dealer has a
small card (2-3-4-5-6), stand on
hands of 13-14-15-16. Draw to
12 if the dealer has 2 or 3.

2. When the dealer has a
large card (7-8-9-1 0-ace), draw
until a count of 17 or greater is
reached.

3. Double down when you
have:

Hard 10 except when dealer has
10 or ace

Hard 9 except when dealer has
7 through ace
Hard 11, always
Ace-2 through ace-5 when deal-
er has 4-5-6

Ace-6 when dealer has 2
through 6

Ace-7 when dealer has 3
through 6

4. Split pairs when you have:
2s when dealer has 3 through 7
3s when dealer has 4 through 7
6s when dealer has 2 through 6
7s when dealer has 2 through 7
9s when dealer has anything
but ace-7-10

Always split aces, eights

5. For ace-2 through ace-6,
draw a card if not able to dou-
ble down.

6. When holding ace-7:

Stand if dealer has ace-2-7-8
Double down if dea er has 3-4-5-
6

Draw if dealer has 9 or 10

7. Always stand on ace-8,
ace-9

These rules are summarized
in Fig. 1, which diagrams the
correct selections for the possi-
ble combinations of two cards
held by the player and the visi-

78 Microcomputing January 1980

Program Hsting. SWTP Blackjack tutor.

0512 IF Dl> 10 THEN Dl-10

0514 IF P10P2 GOTO 570

0520 REM PLAYER HAS A PAIR OF LIKE CARDS

0005 PRINT

0545 REM GET THE CORRECT ACTION FROM THE PAIRS TABLE

0010 PRINT "BLACKJACK STRATEGY TUTOR"

0550 Q*P( VI , D1 )

0020 PRINT "VERSION 2-8-79"

0560 GOTO 740

0030 L 1 NE= 80

0565 REM CHECK EITHER PLAYER CARD AN ACE

0035 REM CREATE MATRICES

0570 IF PlOl THEN IF P2<>1 THEN 670

0036 REM P - FOR WHEN PLAYER HAS A PAIR

0575 REM ONE CARD AN ACE, CHECK FOR BLACKJACK

0037 REM S - FOR WHEN PLAYER HAS A SOFT COUNT (ONE CARD AN ACE)

0580 IF Pl<10 THEN IF P2<10 THEN 630

0038 REM H - FOR WHEN PLAYER HAS A HARD COUNT

0590 REM PLAYER HAS A BLACKJACK1

0039 REM C$, T$ - FOR DESCRIPTIVE WORDS DURING PLAY

0600 Q-5

0040 DIM P(10,10),S(8,10),H(8,10),C$(13),T$(4)

0610 GOTO 740

0050 PRINT "WOULD YOU LIKE INSTRUCTIONS?"

0620 REM PLAYER HAS A SOFT COUNT (ONE CARD AN ACE)

0060 INPUT 1$

0625 REM CORRECT TABLE INDEX

0070 IF LEFTS ( 1 $ , 1 ) a "N" THEN 180

0630 R-R-2

0080 PRINT "YOU AS THE PLAYER WILL BE DEALT BLACKJACK HANDS AND"

0635 REM GET CORRECT RESPONSE FROM SOFT TABLE

0090 PRINT "SHOWN THE DEALER'S UP CARD. JUST AS AT THE TABLE, YOU"

0640 Q-S ( R, D1 )

0100 PRINT "WILL THEN HAVE FOUR OPTIONS:"

0650 GOTO 740

0110 PRINT " STAND PAT (STAND OR ST)"

0660 REM PLAYER HAS A HARD COUNT (NEITHER CARD AN ACE)

0120 PRINT " SPLIT PAIRS (SPLIT OR SP)"

0665 REM IF COUNT>17 OR COUNT<9 THEN OBVIOUS STAND OR DRAW

0130 PRINT " DOUBLE DOWN (DOUBLE OR DO)"

0670 Q-l

0140 PRINT " DRAW A CARD (DRAW OR DR)"

0680 IF R>16 THEN ON Z GOTO 740,460

0150 PRINT "THE TUTOR WILL THEN ADVISE YOU IF YOUR ACTION IS"

0690 Q-4

0160 PRINT "CORRECT BASED UPON BASIC BLACKJACK STRATEGY. YOU"

0700 IF R<9 THEN ON Z GOTO 7l>0,460

0170 PRINT "MAY ENTER END AT ANY TIME TO HALT THE EXERCISE."

0705 REM OTHERWISE CORRECT TABLE INDEX

0180 PRINT "GOOD LUCK... ENTER ANY NUMBER TO BEGIN.."

0710 R-R-8

0190 INPUT 1

0715 REM AND GET CORRECT RESPONSE FROM HARD TABLE

0192 PRINT

0720 Q-H ( R, D1 )

0195 REM SEED THE RANDOM NUMBER GENERATOR

0730 REM PUT THE HAND OUT TO THE TERMINAL

0200 X-RND( 1 )

0740 PRINT

0201 REM SET FOR ALLOWING 'OBVIOUS' HANDS

0750 PRINT "HERE WE GO SAYS THE DEALER..."

0202 Z-l

0755 PRINT

0203 PRINT "DO YOU WISH TO BE DEALT HANDS WITH HARD"

0756 PRINT

0204 PRINT "COUNTS OF 8 OR LESS AND 17 OR MORE?"

0760 PRINT "THE DEALERS UP CARD IS ";C$(D)

0205 INPUT 1$

0770 PRINT

0206 IF LEFTS ( 1 $, 1)-"Y" GOTO 210

0780 PRINT "YOU HAVE ";C$(Pl)j" - ";C$(P2)

0207 REM SET TO IGNORE OBVIOUS HANDS

0790 PRINT

0208 Z-2

0800 PRINT

0209 REM ASSIGN VALUES TO THE MATRICES

0810 IF Q<>5 GOTO 870

0210 FOR J«1 TO 10

0820 PRINT "YOU HAVE A BLACKJACK1 1 NO SELECTION IS NEEDED."

0220 FOR 1-1 TO 10

0825 B-B+l

0230 READ P(I,J)

0830 PRINT "PRESS RETURN FOR NEXT HAND.."

0240 IF 1 <9 READ S( 1 , J ) , H( 1 , J )

0835 A-A+l

0250 NEXT 1

0840 INPUT 1$

0260 NEXT J

0850 IF 1 $ -"END" GOTO 1140

0265 REM CORRECT SELECTION TABLES

0860 GOTO 460

0266 REM 1-STAND

0870 PRINT "IT'S UP TO YOU..."

0267 REM 2-SPLIT

0880 PRINT "YOUR CHOICE? SAYS THE DEALER..."

0268 REM 3-DOUBLE

0890 INPUT 1$

0269 REM 4-DRAW

0895 REM GET INDEX OF PLAYERS RESPONSE

0270 DATA 2, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 1, 4, 4, 1, 4, 2, 1, 4, 1, 1

0900 R$-LEFT$ ( 1 $, 2 )

0280 DATA 2, 4, 3, 2, 4, 3, 2, 4, 3, 4, 4, 4, 3, 3, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1

0905 IF R$-"EN" GOTO 1140

0290 DATA 2, 4, 3, 2, 4, 3, 2, 4, 3, 4, 4, 4, 3, 3, 1, 2, 3, 1, 2, 1, 1, 2, 1, 1, 2, 1

0910 FOR 1-1 TO 4

0300 DATA 2, 3, 3, 2, 3, 3, 2, 3, 3, 4, 3, 1,3, 3,1,2, 3, 1,2, 1,1, 2, 1,1, 2,1

0920 IF R$«LEFT*(T$( 1 ),2) GOTO 970

0310 DATA 2, 3, 3, 2, 3, 3, 2, 3, 3, 2, 3, 1,3, 3, 1,2, 3, 1,2, 1,1, 2, 1,1, 2,1

0930 NEXT 1

0320 DATA 2 , 3, 3, 2, 3, 3, 2 , 3, 3, 4, 3, 1, 3, 3 , 1, 2 , 3, 1, 2, 1, 1, 2 , 1, 1, 2 , 1

0940 PRINT 1$;" IS AN INVALID RESPONSE"

0330 DATA 2, 4, 4, 2, 4, 3, 2, 4, 3, 4, 4, 4, 3, 4, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 1, 1

0950 PRINT "HERE'S THE HAND AGAIN"

0340 DATA 2, 4, 4 , 4, 4, 3, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 1, 4, 2, 1 , 4, 2, 1, 4, 2 , 1

0960 GOTO 755

0350 DATA 2, 4, 4, 4, 4, 3, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 1, 4, 2, 1, 4, 2, 1

0970 IF IOQ GOTO 1060

0360 DATA 2, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 1, 4, 2, 1, 4, 1, 1

0974 C-C+l

0370 FOR 1-1 TO 13

0975 REM THE PLAYER HAS CHOSEN CORRECTLY

0380 READ CS(I )

0980 X- 1 NT( 3 *RND + 1 )

0390 IF 1 <5 READ T$(l)

0990 ON X GOTO 1000,1020,1040

0400 NEXT 1

1000 PRINT "VERY GOOD ... CORRECT RESPONSE.."

0410 DATA "ACE", "STAND", "DUECE", "SPLIT THE PAIR", "TREY"

1010 GOTO 830

0420 DATA "DOUBLE DOWN", "FOUR", "DRAW A CARD", "F 1 VE", "S 1 X"

1020 PRINT "EXCELLENT. CORRECT CHOICE..."

0430 DATA "SEVEN", "E 1 GHT", "N 1 NE", "TEN", "JACK", "QUEEN", "K 1 NG"

1030 GOTO 830

0435 REM INITIALIZE HAND (A), CORRECT (C) AND BLACKJACK (B) COUNTERS

1040 PRINT "THE DEALER SMILES KNOWINGLY AT YOUR WISDOM..."

0440 A-0

1050 GOTO 830

0445 B-0

1055 REM THE PLAYER HAS CHOSEN INCORRECTLY

0450 C-0

1060 X- 1 NT ( 3*RND+1 )

0455 REM DEAL THE PLAYERS HAND (PI AND P2) AND THE DEALERS

1070 ON X GOTO 1080,1100,1120

0456 REM UP CARD (D)

1080 PRINT "NO, THE CORRECT ACTION IS ";T$(Q)

0460 P1»INT(13*RND+1)

1090 GOTO 830

0470 P2- 1 NT( 13*RND+1 )

1100 PRINT "BREAK TIME. . . ";T$( Q) j " IS THE CORRECT CHOICE.."

0480 0- 1 NT ( 1 3*RND+1 )

1110 GOTO 830

0490 REM DETERMINE THE CORRECT RESPONSE FOR THESE CARDS

1120 PRINT "THE DEALER FROWNS... HE EXPECTED YOU TO ";T$(Q)

0495 REM TREAT ALL FACE CARDS AS 1 0 COUNT

1130 GOTO 830

0500 Vl-Pl

1135 REM END SELECTED, PRINT ATTEMPTS, CORRECT COUNTS

0502 V2-P2

1140 PRINT

0504 IF Vl>10 THEN Vl-10

1144 PRINT "YOU HAVE PLAYED ";A; "HANDS. YOU HAVE CHOSEN THE"

0506 IF V2>10 THEN V2-10

1150 PRINT "CORRECT PLAY ";C;"TIMES AND HAD ";B;"BLACKJACKS."

0508 R-V1+V2

1160 PRINT "TRY AGAIN SOON..."

0510 Dl-D

1170 END

ble card held by the dealer. Use
of this strategy will allow the
player to give the casino a
good, stiff battle in Blackjack.
In fact, use of this strategy will
cut the house percentage to
less than one percent, an al-
most even money bet.

You must believe, though,
that the actions indicated by
these rules are absolutely cor-
rect. Selections other than
those shown in Fig. 1 will only
lessen the player’s probable

success. This, then, is the strat-
egy upon which the tutor will re-
ly in its determination of the
correct choice for each hand
dealt to the player.

How the Tutor Works

The Blackjack tutor is set up
to generate random practice
hands of Blackjack and test the
player’s ability to make the cor-
rect strategic choice for the
hand. In the play of a given hand,
the tutor generates three ran-

dom cards— two for the play-
er and a third for the dealer.
Based upon the values of these
cards, the tutor determines the
correct action from a table
based on the strategy outlined
above.

If the player has a Blackjack
(an ace and a ten-count card),
the hand is over. The tutor as-
sumes that any would-be player
of Blackjack will know what
one is and know not to draw to
it! For player hands other than

Blackjack^ the tutor will ask for
the player to select an action.
The player has four choices:

1. Draw a card (enter draw or
dr)

2. Stand pat (enter stand or st)

3. Split pair (enter split or sp)

4. Double down (enter double
or do)

The player’s choice is com-
pared to the correct action the
tutor expects, and an appropri-
ate congratulations or condol-
ence message is printed. If the

Microcomputing January 1980 79

player chooses incorrectly, the
tutor will also advise the player
what the correct action is for
the hand. This allows the player
to immediately correct his
thinking for the conditions dis-
played and is the one item that
sets the Blackjack tutor apart
from other computer Blackjack
games.

The Tutor Program

The Blackjack tutor is written
in SWTP 8K BASIC Version 2.0,
but is written to be easily adapt-
able to other versions of BASIC.

I used only single statements
per line and also avoided
unusual statement types as
much as possible.

The program is well com-
mented and thus self-explana-
tory. To conserve memory or
avoid keying, all line references
are structured such that all
REM (remark) statements can
be removed without affecting
the operation of the program.
However, this alone will not al-
low the program to run on a 12K
system; 16K is the minimum
system required. If operation
on a 12K system is required,
elimination of lines 980-1030,
1070-1110 and possibly the in-
structions will be necessary.

In addition to the basic pro-
gram operation described
above, there are a couple of ad-
ditional significant features. As
a player uses the tutor and be-
comes more practiced, some

hands become old hat. Among
these are hands with hard
counts of 8 or less or 17 or
more. The correct action for
these hands is pretty obvious,
even for the beginner. At this
point, the player might wish to
concentrate his practice on
hands that are not quite so ob-
vious. The tutor allows the play-
er to select this option before
the play begins.

The tutor will also keep a run-
ning total of the number of
hands played, the number of
correct choices made by the
player and the number of Black-
jacks dealt to the player. When
END is entered by the player to
end the session, a summary of
these counts will be printed.

Final Comments

After completing the BASIC
version of the Blackjack tutor, I
also wrote a version in 6502 as-
sembler for the KIM-1. This pro-
gram occupies about 700 bytes
of RAM and uses the KIM’s key-
pad and display for input/out-
put. The entries and displays
are not nearly so elegant as in
the BASIC version, but the
strategy taught is identical.
Thus, its usefulness as a learn-
ing tool for the game of Black-
jack is no less than that of its
bigger brother.

I will provide an object code
listing and description of oper-
ation to interested persons for
the cost of mailing and repro-

duction. My friend Ted, in fact,
has used the KIM version as
one of his prime practice tools.
And as for Ted, well, he’s yet to

hit the felt tables, but after all
of his tutor-guided practice, he
has visions of sacks of silver
dollars. ■

BLACKJACK STRATEGY TUTOR
VERSION 2-8-79

WOULD YOU LIKE INSTRUCTIONS?

? NO

GOOD LUCK... ENTER ANY NUMBER TO BEGIN..

? 1

DO YOU WISH TO BE DEALT HANDS WITH HARD
COUNTS OF 8 OR LESS AND 17 OR MORE?

? NO

HERE WE GO SAYS THE DEALER...

THE DEALERS UP CARD IS JACK

YOU HAVE KING - DUECE

IT'S UP TO YOU...

YOUR CHOICE? SAYS THE DEALER...

? DRAW

EXCELLENT. CORRECT CHOICE...

PRESS RETURN FOR NEXT HAND..

?

HERE WE GO SAYS THE DEALER...

THE DEALERS UP CARO IS FIVE

YOU HAVE NINE - SIX

IT'S UP TO YOU...

YOUR CHOICE? SAYS THE DEALER...

? STAND

VERY GOOD. . .CORRECT RESPONSE..

PRESS RETURN FOR NEXT HAND..

?

HERE WE GO SAYS THE DEALER...

THE DEALERS UP CARD IS FOUR

YOU HAVE SEVEN - TREY

IT'S UP TO YOU...

YOUR CHOICE? SAYS THE DEALER...

? DRAW

THE DEALER FROWNS... HE EXPECTED YOU TO DOUBLE DOWN
PRESS RETURN FOR NEXT HAN0..

? END

YOU HAVE PLAYED 3 HANDS. YOU HAVE CHOSEN THE
CORRECT PLAY 2 TIMES AND HAD 0 BLACKJACKS.

TRY AGAIN SOON...

Sample run.

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80 Microcomputing January 1980

I Mi I Mil SINIiaii Flow

Dinners dssniiaftoi deinsleMei

Dr. Lichen Wang is a physicist who learned programming simply to
make his job easier. Dr. Wang has authored several highly significant
software systems for personal computers. His first popular and
famous program was the kaleidoscope program for the Cromemco
dazzler video board. Dr. Wang is the author of Palo Alto Tiny Basic
which appeared later in an expanded version as Cromemco Control
Basic and was also used as the basis for TRS-80 Level I Basic. Dr.
Wang wrote a robot control language called “WSFN” [Which
Stands For Nothing] that can drive x-y access devices and uses very
unique concepts to allow reiterative shorthand code to draw re-
petitive shapes. Most of the prolific output of Dr. Wang has been
given away and freely published for use and modification by
hobbyists.

THE EXATRON STRINGY
FLOPPY

For new readers, the ESF is
a mass storage subsystem for
microcomputers. Because of its
speed and reliability, it does
away with all the objections of
using audio tape, and audio re-
cording and playback techniques,
without going to the expense of
acquiring disk subsystems. The
ESF is available for the TRS-80,
SWTP or other 6800 systems,
and S-100 bus systems. The TRS-
80 version is a complete unit,
ready to plug in and go, and as
simple to use as the TRS-80
itself. It will load a 4K program
in 6 seconds without error, and
can save up to 40K on the
longer tapes. Use our toll-free
line below to ask for the infor-
mation packet on the ESF.

ESF WORKSHOP

You would have been amazed
to see what went on at a recent
Saturday morning ESFOA work-
shop. Present was a wide range
of Exatron Stringy Floppy own-
ers and enthusiasts: professional
programmers, gifted amateurs,
beginners in microcomputing,
and some brand new ESF own-
ers. Several encouraging wives
were there. After exchanging in-
formation on what each owner
was doing, and questions and
answers, there were several dem-
onstrations of new programs and
projects. One new owner showed
us “WORM”, a fascinating little
graphics program with a worm
wiggling his way all around the
screen at random. Another had
prepared his family and friends
for Halloween by writing an in-
teractive program with graphics
and story line -scary face, star-
tling displays, humorous dialog,
and all! Others had intensively
exercised the new data I/O func-
tions (see below) for the TRS-80
version of the ESF, and had
comments on the fine points of
using data files. Long after the
normal end of the meeting, the
plant office and conference area
was still full, with guys who
didn’t know learning from guys
who did, with more detailed ex-
changes on individual projects,

Secretary , Fred Waters

and with discussion of what to
do next.

ESFOA CHAPTERS ALL OVER

Well, you can do it too!
We’ve had a number of inquiries
from ESF owners around the
US about other owners nearby.
As the nationwide density of
owners increases, clusters grow
in the more populated areas. So
we have a plan under way to
get you together, to inform
you of nearby colleagues. Then
you too will have the benefits
of meeting and exchanging in-
formation on techniques, pro-
grams, new applications and hard-
ware augmentations.

HANDLING DATA FILES

Along with the firmware built
in the ESF, you also get another
significant piece of software- the
Data I/O Program for the TRS-
80 version, on ESF wafer. The
ROM has the programs for certi-
fying new wafers, and for saving
and loading BASIC and assembly
language programs. The subrou-
tines needed for data file hand-
ling are also in the ROM, and
assembly language programmers
can use them. Those who prefer
BASIC can use the Data I/O Pro-
gram. It resides in RAM, and is
delivered on ESF wafer with
your system.

Well, what does it do? Those
of you who have fooled with
larger computers or have used
disks probably already know.
Let’s look at an example. Say
you have a household or small
business inventory program in
your TRS-80. The program has
provision for entering items and
related data, for reporting quant-
ities, for flagging recorder re-
order points, for processing cost
and price data, and so forth. So
you take an inventory as of
January 1. Now all the data you
have in the file -the raw material
on which your program operates,
and which changes periodically -
needs to be retained until the
next inventory. At that time the
present data is the starting point
for the changes that have oc-
curred. So you need to save the
data on your storage medium,
ready to process the next time
you use the program.

The syntax for the Data I/O
Program provides first for OPEN-
ing a numbered file on a selected
drive unit. Up to eight Stringy
Floppys can be operated with
one TRS-80, and there can be up
to 99 files on one wafer. You
may open one file on each drive
unit in your system, if needed.
Next you use the command
“@PRINT”, following by a list
of expressions (constants, var-
iables and operators) to save on
tape the values of the selected
expressions. Finally you use the
“@CLOSE” command to close
the file. For multi-drive systems
there is provision for designating
the current drive, for closing all
open files at once, and for clear-
ing all variables and arrays.

When you want to retrieve
the data, you again use the
“@OPENn” command (n is the
file number), and then load the
data by using the “@INPUT”
command, followed by a list of
variables. These variables must
match in type the expressions
saved, and their values are loaded
into memory. Again you must
close the file, and you may select
another drive unit or clear all
variables and arrays as before.

An important point: all the
commands for data I/O can be
used as program statements, just
as the commands for loading
BASIC and assembly language

I HOT LINE
I

I WITHIN CALIFORNIA

programs can. This means that
you can write your BASIC pro-
gram to include the functions
both of creating and processing
the data you are interested in,
and of storing it on a data file
wafer until needed again. You
can probably think of-or already
have thought of- many applica-
tions around the home or in a
small business where you need
data files.

In passing: probably the most
important single conceptual fea-
ture of the Exatron Stringy
Floppy is its total adaptability
to any software capability you
can imagine. If you need a par-
ticular microcomputer applica-
tion, and if a program can be
written to carry it out, the ESF
can handle it for you.

INFORMATION & ORDERS

The ESF is assembled and
tested at the factory, with a 30-
day moneyback guarantee and
a one-year full warranty. Base
price for the TRS-80 ESF:
$249.50. For the S-100 ESF:
$289.50. For SWTP: $250.00.
Place credit card or COD orders
using the toll-free line below for
fastest delivery.

User’s Manuals and a com-
plete information packet is avail-
able for all versions of the ESF
at no charge.

800 - 538-8559

408 - 737-7111

If you have any questions about these products, about Exatron, or
about ESFOA, call the Hot Line. Address letters to ESFOA, 3559
Ryder St., Santa Clara, CA 95051.

Stringy Floppy is a trademark of Exatron Corporation »^E48

• COMPARE AND SAVE

The FD-200 drive from ACS lets you store 102.4k bytes of
data on one side of the disk. ..compared to only 80k bytes
on a TRS-80 "mini-disk drive. ...and 102.4k bytes on the
other side, as well. That’s almost 205k bytes per mini-disk,
something you can’t do with a TRS-80 “drive.

Completely compatable with your TRS-807 Can be used
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Add $20.00 for DOS 3.0 disk
after September 1 , 1 979.

m Orders received by 6:00 p.m. shipped
within 3 days on Master Charge, Visa,
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■B; Personal Checks require 14 days to
J clear. No C.O.D. Collect calls not
accepted. All Hardware warrented for 90 days.
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Prices subject to change without notice.

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PROGRAM

GALACTIC BLOCKADE RUNNER
SCI-FI GAME SAMPLER
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SYSCOP

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SNAKE EGG
LIFE 2
DCV-1

MUSIC MASTER
DISK MUSIC MASTER
TRS-80 CP/M

DESCRIPTION

• AN EXCITING SPACE WAR GAME WITH GRAPHICS

TRS-80

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i/* Reader Service— see page 227

Microcomputing January 1980 83

An Operator-Oriented
Data Base

Management System

This three-part article on managing data begins with a description of the system.

Joel Shapiro

491 Kenilworth Court

Des Plaines IL 60016

I t all started when I decided I
needed another program that
could generate some new files
for storing catalog data. Going
back through the many applica-
tions programs I had written in
the past, I was amazed at the
number of different file formats I
had generated for my programs.
As anything less than standard-
ization is unforgivable in my pro-
fession (manufacturing), I de-
cided to do something about it.

Introduction

The computer at home is used
for a part-time computer service
run by my wife and as a tool with
which I can develop business
software. A data base manage-
ment system would be helpful
for both uses. Considering my
wife’s background in office pro-
cedure (former secretary and
word-processing department su-
pervisor), I could make the pro-
gram compatible with the man-
ual systems used in many small
businesses.

The problem I’ve run into in
the past is that many existing

programs support a long learn-
ing curve from the operator
training viewpoint. The unfortu-
nate thing about this is that
most small businesses will not
use a computer if it won’t fit into
their existing procedures with a
minimum of effort and change.
Anticipating this and the fact
that many readers would like
this type of program, I decided
to incorporate many prompts
and error-trapping routines in
the program.

As a businessman with some
years of experience as a manu-
facturing executive, I am famil-
iar with data base systems from
the user’s viewpoint. This has
helped in developing this pro-
gram in that many of the fea-
tures of some existing commer-
cial programs are not used and
other features are desired.

I have selfishly written the
program with my own preju-
dices in mind, and I believe an
operator, with very little training,
can make use of the system. No
attempt has been made to con-
serve memory or increase speed
at the expense of operator con-
venience, operator assistance
or system flexibility. The com-
promise in speed is not limiting
for personal computer use and
is within the requirements of a
small business that will use the

computer to supplement a small
staff.

The program was written to
run in my system, which has 48K
of memory. Although much of
the memory is used by the inter-
preter and approximately 2K is
used for the display at the top
end, it has proved to be enough
for the program. The system
also has dual disk drives, each
capable of 31 5K of storage, and
a printer capable of 132 charac-
ters per line. I feel that this may
represent the system a small
business would use.

The programs can be changed
to suit individual systems by use
of the chain feature of Micropo-
lis BASIC for smaller program
segments. The elimination of
many of the prompts, error
traps, messages and remarks
can also save memory, but this
may compromise operator con-
venience and promote error. Ad-
ditionally, a few of the subrou-
tines will have to be changed to
suit the user’s terminal. Those
written in the program support a
Merlin video board, which is not
too common.

Part 1 of this three-part article
will describe the features and
operations of the program, leav-
ing the description of the code
itself for parts 2 and 3. I will
cover explanations of features

used in Micropolis BASIC and
possible changes the reader
may desire.

Program Features

1. Full prompting, with many
error traps, error messages and
subroutines, which make it easy
to learn.

2. Up to 30 fields for data,
each of any length as long as
the total of all fields does not ex-
ceed 248 characters.

3. Field titles up to 18 charac-
ters.

4. Complete edit function for
all data.

5. Data can be deleted from
one file and added to another
automatically.

6. Automatic formatting of
dates.

7. Automatic search for any
entry in any field.

8. Automatic formatting of
dollar fields.

9. Data recovery utility pro-
gram for use in case of program
crashes.

10. File parameters remain
on disk and can be changed by
the user.

11. Report format is selected
by the user, including all ele-
ments of the heading.

12. Report format can be re-
tained on disk for future use as
well.

5 84 Microcomputing January 1980

13. Column spacing is auto-
matic, and program will wrap
around any lines that are too
long for the printer in use.

14. As an option, program
will reverse first and last names.

15. Reports can be made any
length.

1 6. Reports can be made with
data between an upper and low-
er limit as determined by the
user.

17. Numerical and dollar
fields can be totaled at the end
of the report.

18. Multiple level sorting that
can sort up to ten levels is avail-
able. Index files that allow the
same file to be sorted in many
ways are used.

Description

The data base management
system consists of three major
programs or functions: one cre-
ates a file; another allows the

management of data; and the
third provides a printed report
derived from the data. Other pro-
grams in the system provide util-
ity functions such as sorting,
and still others provide for the
access of data from many files
in order to obtain information
for a single report. Application
programs can gather data from
one or several files, manipulate
the data and generate reports or
even more files. The possibili-
ties are endless when the appli-
cation calls for the storage and
manipulation of data.

The reason the data base
management system can have
such unique possibilities is that
all files are accessed and read in
the same manner, so programs
can be written with this stan-
dardization in mind.

The system presented here
covers the three major functions
and provides for sorting and file

recovery in case of a program
crash.

First of all, line 80 is the effec-
tive entry point in each program.
This means that typing GOTO80
in the case of a program crash
will allow reentry into the pro-
gram and restart without loss of
data in most cases. If the com-
puter flashes a FILE OPEN error,
just type CLOSE 1 and then GO-
TO80. A CONTROL C will inter-
rupt processing. The program
disk must be placed in drive
number 0 for proper chaining op-
erations.

Creating A File

The disk used for this file
must have been previously for-
matted by the Micropolis for-
matting routines before a file
can be created.

Operation is initiated by load-
ing the DATABASE program.
When started, the program will

request the date and transfer
control to PROGRAMS. All pro-
grams have a subroutine that
will format the date, and all will
accept input in the following
manner.

When a date is requested, it
must be entered month, day and
year. It can be entered using sin-
gle digits for month and day and
any nonnumeric character be-
tween the groups. This means
that 7 3 75 will be formatted as
07/03/75. If you type 7r3z75, it
will be formatted properly as
well. It is important that all
dates be in the same format for
proper handling in these pro-
grams.

PROGRAMS will display a
menu from which the operator
can choose the desired function
or program, and once chosen,
control will be passed to that
program. Since data is passed
between programs, it is impor-

FILE FACTORY PAYROLL FILF CODE 1

FILE CREATED 07/05/79 FILE UPDATED 07/29/79 14 ENTRIES

CL *

LG

NAME

HR/PAY SOC SEC #

EXMT

STREET

DATE HIRE DATE DEPT

STATUS

CITY
EMER PH

EMP PH

ST

ZIP

VAC

DEPT POSITION
NAME EMERGENCY

12111

12

ABBOTT f GEORGE
$ 7.54 888-77-6666

1

345 LENDER AVE
04/31/76 04/31/76

1

MATOON

132-1321

132-1321

IL

62332

1

123 INSPECTOR

ABBOTT f DORIS

02111

11

BROUN f GEORGE
* 6.93 131-31-3113

6

99 DENVER AVE
06/03/74 07/07/78

2

ALBION

343-3232

343-3232

IL

67766

4

245 INSPECTOR

BROUNf ESTHER J.

10222

11

BROUN f MARYANN E.

♦ 6.50 303-03-3030

1

678 N. MARINE DR.
06/07/78 06/07/78

1

CHICAGO

123-9876

123-9876

IL

60606

0

300 CLERICAL

BROUNf ESTHER

22021

12

BROUNEr KAREN J.

♦ 7.75 535-53-3535

2

19 UOODDALE AVE
01/21/72 01/21/79

1

CANOGA

333-3333

333-3333

IL

66600

1

123 SUPERVISOR

BROWNE f JOHN

32113

23

HUDSONr DANIEL J.

♦ 25.00 444-66-8888

2

55 NORTH AVE
04/04/69 06/07/78

1

CHICAGO

355-6879

355-6879

IL

60789

4

123 BOSS

HUDSONf JANE

00122

9

JOHNSON f JAMES C.

$ 5.50 222-33-4444

3

8954 WOODVILLE AVE
06/15/76 06/15/76

1

DEMPSEY

444-5555

444-5555

IL

61123

1

105 MACH. OPERATOR

UOODSf DORIS

00101

23

JONESf KEITH
♦ 13.50 999-99-9999

4

999 WEST DRIVE
05/12/66 05/05/78

1

SAMPSON

222-1122

222-1122

IA

23999

4

111 SALESMAN

JONESf BETTY

54321

10

METZ f GLADYS G*

% 5.80 866-54-9002

1

54 UINDSON LANE
05/13/76 12/12/78

1

CRETE

662-4578

566-1221

IL

61134

2

112 OFFICE CLERICAL

METZ t JOHN

00121

8

PASTERNACK f LAURENCE
* 5.25 444-56-1234

1

23 PANSY LANE
0 7/07/77 08/01/78

1

ODESSA

NONE

234-2345

IL

60111

0

105 JR. OPERATOR

NONE

11056

10

PETERSONf GERALD
♦ 5.80 234-76-9456

1

886 FORMOST DR.
09/21/78 08/21/78

1

UINNEBAGO

555-3456

555-3456

IN

47768

0

116 OFFICE CLERICAL

PETERSONf HAROLD

00123

13

SMITHf ROGER
• 8.45 111-22-3333

5

345 UOOD AVE
05/06/73 06/22/75

1

ASPEN

234-5678

234-5678

IL

60894

2

103 MACHINIST

SMITHf BETTY

00111

12

VALDEZ f JUAN
t 7.93 102-23-5678

2

134 E. 54TH ST
05/12/75 08/19/77

1

AKRON

335-6789

335-6789

IL

60923

2

103 MACHINIST

VALDEZ f GLORIA

10987

41

WYNN f EDUARD 8*

% 50.00 111-55-7777

4

244 LAMPSON DR.
04/31/67 03/31/78

1

CLARK

666-9944

666-9944

IL

61138

5

124 MANAGER

WYNNf bertha

TOTAL HR/PAY - ♦ 155*95

Listing 1. Entire file— alphabetical sort.

Microcomputing January 1980 85 5

FILE FACTORY PAYROLL

FILE CODE 1

FILE CREATED 07/05/79

FILE UPDATED 07/29/79

14 ENTRIES

NAME

STREET

CITY

ST

ZIP

GEORGE ABBOTT

345 LENDER AVE

MATOON

IL

62332

GEORGE BROUN

99 DENVER AVE

ALBION

IL

67766

MARYANN E. BROUN

678 N . MARINE DR*

CHICAGO

IL

60606

KAREN J. BROUNE

19 UOODDALE AVE

CANOGA

IL

66600

DANIEL J. HUDSON

55 NORTH AVE

CHICAGO

IL

60789

JAMES C. JOHNSON

8954 UOODVILLE AVE

DEMPSEY

IL

61123

KEITH JONES

999 WEST DRIVE

SAMPSON

IA

23999

GLADYS G » METZ

54 UINDSON LANE

CRETE

IL

61134

LAURENCE PASTERNACK

23 PANSY LANE

ODESSA

IL

60111

GERALD PETERSON

886 FORMOST DR.

WINNEBAGO

IN

47768

ROGER SMITH

345 WOOD AVE

ASPEN

IL

60894

JUAN VALDEZ

134 E. 54TH ST

AKRON

IL

60923

EDUARD G. UYNN

244 LAMPSON DR.

CLARK

IL

61138

Listing 2. Address list name sort .

tant that DATABASE be the first
program used.

The CREATE program pro-
vides all of the functions re-
quired for creating the file itself,
the parameters of which are
written into the first five records
of the file. Information written
into the file by this program is as
follows:

File code— I use a numerical
code (0-99) to control file access
by application programs. It can
be alphanumeric and up to 30
characters long if desired.
Special filename/purpose — A
string of up to 30 characters—
used on reports if actual file-
name is to be guarded or if pur-
pose such as Payroll, Mail List,
etc., is to be printed on the re-
port.

Number of fields— Added by
program when file is created.
File create date— Date entered
when program was initialized
and CREATE program used to
create a file.

All of this data is written into
record 1 of the file. Additional in-
formation such as print options,
records to be deleted, file up-
dates, etc., which are used else-
where in the system, will also be
retained in record 1. This saves
time in reentering a lot of data
and also provides continuity to
the system.

The title, size, type code and
operator access key for each
field is written into records 2-4.
Fields— A field is where a sin-
gle element of data is stored.
The data is accessed from the
file by accessing the field. If
you picture a printed report
with several columns, each
column will represent a sepa-
rate field.

Each field must have a title; a
maximum of 18 characters is al-
lowed for each title. Certain fea-
tures, which are described later,
are keyed into a portion of the ti-
tle, so the title for the field must
be decided carefully.

When data is entered into a
field, blanks are added to fill out
the data string to the selected
field length. This is done so the
field data can be accessed cor-
rectly in all routines. The field
codes (N, S and D, meaning nu-
merical, string and dollar, re-
spectively) determine how this
is done. All S fields are padded
from the right so all string data
is left justified when printed. All
N fields are padded from the left
and are right justified. D fields
are padded from the right, but
are formatted in the REPORT
program.

It is extremely important that
the size of a D field allow for the
the decimal point and 1/100s
(cents) in addition to the space
required for whole dollars. No
space need be allotted for a dol-
lar sign or commas, as these will
be added in the REPORT pro-
gram.

If a decimal point is used in N
fields, don’t expect them to line
up in printed reports. Because
the number of digits to the right
of the decimal point is not al-
ways known, the field cannot be
readily formatted. However,
data consisting of a whole num-
ber will be right justified.

Certain features are keyed
from the first four characters of
a field title. When read as name,
the field is designated as S, and
subsequent programs will allow
reversal of the first and last
names. Names should be en-

tered as follows for correct pro-
cessing: enter the last name,
comma, space and first name.
The program will search the
string for the comma and re-
verse the string from that point.

When read as date, all pro-
grams will provide for correct
formatting of the date string. All
dates must be in a date field for
proper handling of the data.

When the first four characters
are read as AMT., the field is set
as a D field. If you don’t want to
use AMT. in the title, it is still
possible to designate the field
as a D field. Correct formatting
will not occur if the field is not
coded D.

File Maintenance

The file maintenance pro-
gram, MAINT, is responsible for
controlling data entry, editing
and removal with regard to the
file. When MAINT is called by
DATABASE, a menu to allow se-
lection of one of its many func-
tions will be displayed.

After a filename is given, the
program causes the computer
to search for the file. In a multi-
ple drive system such as mine,
drive 0 is checked first, and if the
file has not been found, drive 1 is
checked. If the file is not found
on either drive, then an error
message is displayed. When the
file is found, the first five rec-
ords are read and some of the in-
formation is displayed on the
screen. The operator can then
add data, delete, modify (edit),
search and review the file en-
tries as desired. The file is up-
dated as each record is modi-
fied or added.

An auto delete function will
allow deletion coding of all rec-

ords in which the entries within
a selected field are between up-
per and lower limits as selected
by the operator. This does save
considerable time whenever a
group of entries are to be de-
leted.

Note at this time that the rec-
ords are only coded for deletion.
When so coded, they will not be
displayed, printed or used in
other programs except SORT-
FILE. Records coded for dele-
tion, however, can have the cod-
ing removed within the modify
function of the MAINT program.
The program was written this
way because restacking the file
(which removes the coded data)
does take considerable time.
This is something you may wish
to do when you have it, or when
you need the file space.

The DELETE program has the
responsibility for this function.
DELETE is chained from MAINT
and is considered part of the
MAINT program. When the data
has been deleted and the file re-
stacked, any unused tracks are
reallocated as open tracks.

Options available in the pro-
gram include transferring coded
data to another file or just delet-
ing the data.

In the case of deleting to an-
other file, the file parameters
must be the same in both files;
the only difference can be in the
filename. For this reason, the
utility routine in the CREATE
program, which duplicates the
file parameters, should be used.
Coded records transferred to
the file before deletion will be
added in sequential order and in
the order in which they are
transferred. The main reason for
transferring to another file is to
allow deletion of data from ac-
tive files and storage of this
data for historical reference.

Sorting

The SORTFILE program is ca-
pable of multiple-level sorting.
This means that it has the capa-
bility of sorting into major cate-
gories and minor categories,
each within the other. For in-
stance, with a mailing list file
you can first sort by state, then
zip code within a state, town
within a zip code and street
within a town.

When the program is called, it

5 86 Microcomputing January 1980

will request the primary sort
field (which should be a major
category) and the subsequent
minor fields. Up to ten levels can
be sorted in this fashion. Take
care in choosing the primary
field. If name is a primary field in
a sort of many levels, there will
be no apparent sort unless
many John Smiths are in the file.

Sorting takes time! The more
levels selected, the more fields
in the file, the more data to sort
and the longer it takes. In my
tests, 100 entries in a four field,
two level sort took 7 1/2 minutes.
Nine hundred entries in the
same file took 1 1/2 hours.

As sorting takes place the
screen will show a descending
progression of numbers. This is
only to show the operation of
the program and the progress of
the sorting task. The closer to
zero, the closer it is to comple-
tion.

When the file has been
sorted, the locations of the
sorted entries in the master file
are located in an index file. The
index file stores data in a dif-
ferent format than do the data
files. Index information for 1200
file records can be stored in only
three tracks of index file. In
most cases, this will permit you
to store a master file and one or
several index files on a single
disk.

Up to 1160 data entries and
one index file can be placed on a
disk. The maximum number of
data records allowable, using a
full disk, can only be 1211, so the
sacrifice of 51 data entries may
be warranted in keeping the files
together. Don’t worry about it!

After sorting, if the program
determines there is not enough
space on the disk for the index
file, it will advise the operator. A
new index file can then be cre-
ated within the program without
the loss of the stored data. It is
best to create (name) the index
file before starting the sort, but
it can be done the other way
around. The index file can be lo-
cated on another drive without
hampering system operation.

No data is changed in the
sorting process, and the master
file is not changed. Many index
files can be made for the same
master file depending upon the
sorting requirements.

Remember: All file data is
considered in the sort. If data is
added or deleted to or from the
master file, the file will have to
be resorted. If the data is modi-
fied in one of the fields used in
the sort, the file must be re-
sorted. It is therefore best to
make any changes before sort-
ing.

The Report Generator

The REPORT and PRINTER
programs produce the printed
report in one of several different
formats selected by the opera-
tor. I used a kind of “salad bar”
approach in that the report pa-
rameters and features are all op-
erator selected, mainly by an-
swering yes- and no-type ques-
tions.

One of the pet peeves of a
business executive is that he
can’t get the report he wants
without waiting several weeks
for priority in a data processing
department. That has been ex-
pressed to me upon several oc-
casions at various trade meet-
ings and seminars. A good case
for the micro!

It is unfortunate because in
some large businesses that
have large computers, large
sums of money can be lost if the
file information isn’t available.
The impact of the same problem
on a small business can some-
times be disastrous.

Have no fear! I believe this ap-
proach to getting the informa-
tion from the files requires very
little training and can be used by
the person requiring the report
without a problem and, I hope,
without a loss.

When REPORT is called, the
file accessed and the parame-
ters displayed, the operator is
requested to enter the fields (by
number) wanted in the report
and in the desired sequence.
Only the fields requested by the
operator will be printed. If all
fields are to be printed, just en-
ter ALL, and the fields will be
printed in file sequence. If the
letter T is entered directly after
the field number, when the field
is an N or D field, the total
amount for all entries with that
field will be printed at the end of
the report.

The operator is then re-
quested to select other options,

mainly about the report head-
ing. The field selection, options
selected and fields selected for
totals are normally retained in
the file. After the report is
printed, the operator can have
this done by selecting the op-
tion. This way, the information
need not be entered again un-
less there are changes. It is also
possible to generate a report
with a different setup without
destroying the options already
recorded in the file.

After field and option selec-
tion, the operator is asked to in-
sert a new line width if different
from the 132 character default
assignment. This permits the
use of different width paper
without difficulty.

If a name field is to be printed,
the operator is asked if the first
and last names are to be re-
versed. Remember, they are last
name first in the file.

The final feature for selection
is the determination of upper
and lower limits for data in the
report. The default of this option
is to print all entries. Use of the
limit feature permits the opera-

tor to select a field to use for the
control and to set the limits
within that field.

It is therefore a simple matter,
for instance, to select a date
billed field and print out only the
entries with billing between 90
and 120 days old, printing out
the outstanding balance as
well! This feature works along
with the sort so the information
is printed in sorted fashion and
within the selected limits.

The sorting and the limit rou-
tines will work even though the
fields used for either or both of
them are not used in the report.
As you can see, the flexibility of-
fered to the operator is tremen-
dous in that a report may be
printed in a manner tailored for
his needs. The versatility of the
system is further demonstrated
in the sample runs. To assist in
demonstrating the system, I cre-
ated a short file that resembles
what might be considered the
payroll data file for a small busi-
ness.

In Listing 1, the file is printed
in its entirety alphabetically.
Note that when the number of

FILE FACTORY PAYROLL FILE CODE 1

FILE CREATED 07/05/79 FILE

UPDATED 07/29/7?

14 ENTRIES

NAME

DATE HIRE

KEITH JONES

05/12/66

EDUARD G. WYNN

04/31/67

DANIEL J. HUDSON

04/04/69

KAREN J. BROWNE

01/21/72

ROGER SMITH

05/06/73

GEORGE BROUN

06/03/74

JUAN VALDEZ

05/12/75

GEORGE ABBOTT

04/31/76

GLADYS G. METZ

05/13/76

JAMES C. JOHNSON

06/15/76

LAURENCE PASTERNACK

07/07/77

MARYANN E. BROWN

06/07/78

GERALD PETERSON

09/21/78

Listing 3.

Seniority list.

FILE FACTORY PAYROLL FILE CODE 1

FILE CREATED 07/05/7? FILE UPDATED 07/29/79 14 ENTRIES

DEPT

HR/PAY

LG

DATE HIRE

EMER PH

103

*

7.93

12

05/12/75

335-6789

103

4

8.45

13

05/06/73

234-5678

105

4

5.25

8

07/07/77

NONE

105

4

5.50

9

06/15/76

444-5555

111

*

13.50

23

05/12/66

222-1122

112

4

5.80

10

05/13/76

662-4578

116

4

5.80

10

09/21/78

555-3456

123

4

7.54

12

04/31/76

132-1321

123

4

7.75

12

01/21/72

333-3333

123

4

25.00

23

04/04/69

355-687?

124

4

50.00

41

04/31/67

666-9944

245

4

6.93

11

06/03/74

343-3232

300

4

6.50

11

06/07/78

123-9876

TOTAL HR/PAY - • 155.95

Listing 4. Sort by department.

Microcomputing January 1980 87 5

FILE FACTORY PAYROLL

FILE CREATED 07/05/79

FILE CODE 1
FILE UPDATED 07/29/79

14 ENTRIES

NAME

EMER PH

DEPT

GEORGE ABBOTT

132-1321

123

GEORGE BROWN

343-3232

245

MARYANN E. BROUN

123-9874

300

KAREN J. BROWNE

333-3333

123

DANIEL J* HUDSON

355-6879

123

JAMES C. JOHNSON

444-5555

105

KEITH JONES

222-1122

111

GLADYS G. METZ

662-4578

112

LAWRENCE PASTERNACK

NONE

105

GERALD PETERSON

555-3456

116

ROGER SMITH

234-5678

103

JUAN VALDEZ

335-6789

103

EDWARD 0. WYNN

666-9944

124

Listing 6. Sequence of fields has been changed from Listing 5.

FILE FACTORY PAYROLL FILE CODE 1

FILE CREATED 07/05/79

FILE UPDATED 07/29/79 14 ENTRIES

NAME

DEPT

EMER PH

ABBOTT » GEORGE

123

132-1321

BROUN , GEORGE

245

343-3232

BROWN » MARYANN E .

300

123-9876

BROWNE » KAREN J.

123

333-3333

HUDSON » DANIEL J.

123

355-6879

JOHNSON e JAMES C.

105

444-5555

JONES » KEITH

111

222-1122

METZ t GLADYS G.

112

662-4578

PASTERNACK r LAWRENCE

105

NONE

PETERSON r GERALD

116

555-3456

SMITHf ROGER

103

234-5678

VALDEZ r JUAN

103

335-6789

WYNNr EDUARD 0.

124

666-9944

Listing 5.

Emergency phone number list.

columns exceeds the page
length margin, the line is broken
at the beginning of the next field
and a new line is started with an
offset of five characters. The off-
set is provided to allow the read-
er to align the column with the ti-
tle when the report is read. This
report was set for double spac-
ing, which occurs after the line
has been completed. Note also
that the data is aligned with the
first character of the title. This
approach, rather than centering
the title, seems to make it easier
to read.

Note that the total for the
hourly pay (HR/PAY) field is
printed at the bottom of the re-
port.

Column width is determined
by a subroutine that determines
the largest field size, title length
or dollars as formatted. To this,
two spaces that determine the
spacing are added.

Listing 2 is an address list
sorted alphabetically by name;
the first and last names have
been reversed by the program.

Listing 3 is a seniority list
sorted by hire date.

Listing 4 shows a sort by de-
partment, LG (labor grade) and
hourly pay. Note that the hire
date and emergency phone are
also printed. The hourly pay field
is totaled.

Listing 5 is an emergency
phone number list for all em-
ployees. The same alphabetical
sort by name, as used in Listing
2, is used here.

Listing 6 is the same as List-
ing 5, except the sequence of
the fields is changed.

The sample runs shown here
are indicative of the type of re-
port preferred by the business
user, with the flexibility required
by the home computer owner.
However, the report you request

is really limited only to what you
desire, providing it is within the
capabilities of the system.

The Recovery Program

The axiom regarding necessi-
ty and invention applies fully to
my development of the RECOV-
ERY program. One stormy day,
while I was entering data into
my music catalog file, we experi-
enced a power failure in the
area. Although the power failure
was momentary, it was of long
enough duration to drop the
data in RAM. I had started the
day with about 100 entries in the
file and had added about 600
more.

The MAINT program adds the
data to the file as each entry is
complete, but the end of file
marker used by the disk system
was never reset. In other words,
only 100 records of the file could
be accessed by the computer.

The RECOVERY program per-
mits the operator to move (or
step) the end of file marker to
the first incorrect (garbage or
empty) record and reset the
marker. When reading the data
displayed by this program, keep
in mind that the data isn’t bro-
ken down into fields. However, It
is clear enough for the operator
to recognize good data and
make the end of file determina-
tion.

It is a good idea to make a
backup copy of the file before
working with it. It is always pos-
sible to wipe out your data base
due to a hardware or software
fluke in the system.

This completes the descrip-
tion of the features and opera-
tion of the data base manage-
ment system. Next month, in
part 2, we will begin examining
the actual BASIC programs that
comprise the system. ■

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The TNW488/103 Low Speed Modem is Bell 103
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5 88 Microcomputing January 1980

use TRcopy

WITH YOUR LEVEL II TRS-80*

TRcopy is a cassette tape copying system that lets
you SEE what your computer is reading.

COPY ANY CASSETTE TAPE 00

With the TRcopy system you can copy any TRS-
80 Level II cassette tape whether it is coded in
Basic or in machine language. You can also copy
data created by programs and you can copy assem-
bler listings.

YOU CAN SEE THE DATA

As the tape is being loaded, you can SEE the
actual data byte-for-byte from the beginning to the
end of the program. Up to 320 bytes are displayed
at one time. ASCII characters are displayed on the
first line and hexadecimal code is displayed on the
following two lines. Data is displayed exactly as it
is input including memory locations and check sums.

IDENTIFY PROGRAMS

With TRcopy you can identify programs on cas-
sette tapes without written documentation because
you can SEE the filename. If you forget to label a
tape, you can use TRcopy to display the tape contents
and identify the cassette.

VERIFY CASSETTE TAPES

With TRcopy you can verify both the original tape
and the tape copies. You can make certain that your
machine reads the original tape correctly and that it
makes byte-for-byte copies. TRcopy also counts as
it reads giving you the exact length of the data.

MAKE BACKUPS FOR YOUR PROGRAMS

Now you can make backup copies of your valuable
programs. Many times a cassette that you make will
load better than one that is mass produced. The
original can then be kept as a backup in case the
copy is damaged.

MAKE COPIES OF YOUR SOFTWARE

If you are in the software business you can use
TRcopy to make tested copies of your programs for
sales distribution. TRcopy produces machine lan-
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duced by the assembler Itself.

RECOVER FAULTY DATA

With TRcopy you can experiment with the volume
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is possible to read and copy faulty tapes by adjusting
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SIMPLE - FASCINATING - FUN

TRcopy is not only a practical utility program.lt
is also a fascinating graphics program that lets you
SEE, for the first time, cassette data as your com-
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Just load, verify and copy. You will now be able to
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TRcopy is there when you need it.

The TRcopy system is a machine language program
with documentation explaining tape leaders, sync
bytes, check sums and other formatting conventions.
With the TRcopy system, you can SEE what you are
doing!

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Reader Service — see page 227

Microcomputing January 1980 89

Lance E. Rose
COMLABS, Inc.

PO Box 1082
Kalispell MT 59901

A Relocator
for North Star BASIC

See how many uses for this application you can locate in this article.

H aving had about a year’s
experience working with
the North Star minidisk system,

I think I can safely say that it is a
convenient little unit. Both the
hardware and software (DOS

and BASIC) provided seem to be
reasonably well thought out and
work together satisfactorily.
Even though I’ve since acquired
a second drive and some more
sophisticated software, I still
find myself reaching for the
North Star BASIC/DOS combi-
nation when I want to write a
quick and dirty program, be-
cause I can start writing in just
about nothing flat.

The system has a certain sim-
plicity that I find attractive, even
though the file-managing capa-
bilities aren’t quite as conve-
nient as, say, the version of
CP/M for minifloppy systems.
Still, I think most owners will
agree that they now have their
hands on quite a nice, cost-
effective system, especially
when they stop to consider that
most of us who bought such a
system were able to retire older,
less convenient cassette or
paper tape systems.

Lest I be accused of writing
an ad for North Star, I think it’s
only fair to say that I think they
did miss the point on a couple of
matters when they designed
their software. One of my nag-
ging questions has always
been: “Why on earth did they
start the standard DOS at 2000H
instead of something more logi-
cal (0000 H)?”

I’m sure I’m not alone in say-
ing that it can cause some in-
convenience, especially if
you’re running a different sys-
tem part of the time and want

your memory to start at 0000H,
whereas with North Star BASIC
you gain the most space for pro-
grams if your memory is ad-
dressed starting at 2000H.

Although I’ve lived quite nice-
ly with this for a year or so, the
idea struck me recently that it
might be nice to be able to relo-
cate the system to take better
advantage of the available mem-
ory and not have to be constant-
ly readdressing memory boards.
Of course, you can purchase a
custom version of either DOS or
BASIC from North Star for your
own special configuration, but
this requires a minor capital
outlay. Besides, with a relocator
of your own you could create as
many different versions as you
had a use for at no expense or
inconvenience . . . and perhaps
have some fun doing it.

Relocation

To digress for a moment into
the principles involved in mov-
ing a language such as BASIC
from one part of memory to an-
other: The primary obstacle when
dealing with any software writ-
ten for the 8080 is the lack of any
indexed or relative addressing
scheme. This means that a pro-
gram must reside in a particular
part of memory to run correctly.
If it is moved without changes to
somewhere else and then exe-
cuted, all bets are off. And if you
have a memory-mapped video
as I do, you’ll probably see all
sorts of funny patterns sudden-

Relocator program.

10 REM RELOCATOR FOR NORTH STAR BASIC , REL. 4
20 REM WRITTEN BY LANCE E. ROSE, 4/79
3 0 REM

40 REM FIND OUT IF 8 OR 14 DIGIT VERSION
50 PRINT

60 INPUT "8-DIGIT OR 14-DIGIT? ",Q$

70 IF Q$= " " THEN B=8
80 IF Q$="8" THEN B=8
90 IF Q$="l 4 " THEN B=14
100 IF B=0 THEN 60

110 REM GET DRIVE NUMBER TO GET STANDARD BASIC FROM
120 PRINT

130 INPUT "DRIVE NUMBER FOR STANDARD BASIC: ",Q$

140 IF Q$=" " THEN Dl=l
150 IF Q$="l " THEN Dl=l
160 IF Q$="2 " THEN Dl=2
170 IF Q$="3 " THEN Dl=3
180 IF D1=0 THEN 130

190 REM GET DRIVE NUMBER TO PUT NEW BASIC ON
200 PRINT

210 INPUT "DRIVE NUMBER FOR RELOCATED BASIC: ",Q$

220 IF Q $ = " " THEN D2 = l
230 IF Q$="l " THEN D2=l
240 IF Q$="2" THEN D2=2
250 IF Q$=" 3 " THEN D2=3
260 IF D2=0 THEN 210

270 REM GET STARTING ADDRESS FOR NEW BASIC
280 PRINT

290 INPUT "STARTING ADDRESS FOR RELOCATED BASIC(HEX): " , Q$

300 IF Q $ = " " THEN Nl=10752 ELSE GOSUB 3700

310 IF Nl>51712 THEN 290

320 N=N 1

330 0=N-1 0752

340 REM GET ADDRESS FOR DOS USED FOR BASIC'S I/O
350 PRINT

360 INPUT "STARTING ADDRESS FOR DOS TO BE USED(HEX): ",Q$

370 IF Q$="" THEN Nl=8192 ELSE GOSUB 3700

380 IF Nl>604 16 THEN 360

390 REM OPEN THE STANDARD BASIC FILE

400 IF B=8 THEN T$=”BASIC," ELSE T$="BASIC14 , "

410 T$=T$+CHR$ (48+D1)

420 OPEN #0%1,T$,L

430 REM GENERATE NAME BASED ON LOCATION OF NEW BASIC
440 T1=N
450 T$="

460 FOR 1=1 TO 4
470 T=INT (T 1/1 6~ (4 -I ) )

480 T1=T1-16~ (4-1 ) *T

490 IF T<1 0 THEN T$ (I f I ) =CHR$ (4 8+T ) ELSE T$ (I , I)=CHR$ (55+T)
500 NEXT I

510 IF B=8 THEN T$="B08-"+T$ ELSE T$="B14-"+T$

520 T$=T$+" ,"+CHR$ (48+D2)

530 REM IF NEW BASIC FILE EXISTS, DESTROY AND MAKE NEW ONE
540 IF FILE (T $ ) 0-1 THEN DESTROY T$

550 CREATE T$, L, 0
560 OPEN # 1 %0 , T$

570 REM INITIALIZE MEMORY POINTER
580 M=10752

590 REM RELOCATION SECTION - CALLS APPROPRIATE SUBROUTINES
600 REM FOR DIFFERENT SECTIONS

90 Microcomputing January 1980

ly appear on the screen, signify-
ing a software explosion.

The way around this, of
course, is to change all the in-
structions that reference a
memory location so that they
reference a new location offset
by a fixed amount from the origi-
nal one. If you have a source pro-
gram and an assembler, this can
be done by simply changing the
ORG statement at the begin-
ning.

Unfortunately, with very few
exceptions, nobody these days
is interested in providing source
listings for anything as complex
as a BASIC or other high-level
language. The reasons for this
have been argued back and
forth for years without resolu-
tion, but that’s what we’re stuck
with for now.

So, if no source listing is avail-
able, what do you do? The an-
swer is you create one. This is
easier said than done for a lan-
guage as long as BASIC where
the source can easily run
4000-5000 lines. Still, we have
to begin somewhere; since I
have a home-brew disassembler
that provides cross-referenced
listings, that’s just what I did.

Even though the above step
seems to be a tough one, the
most difficult part still remains:
the examination and identifica-
tion of each part of the program
to see whether it consists of in-
structions or data. If the pro-
gram consists of instructions,
you must identify those instruc-
tions that reference memory
locations that must be changed
afid those that ought to be left
alone.

With program data there is a
similar problem In that many ta-
bles contain a sequence of
2-byte addresses referencing
the different locations where
your favorite commands and
functions live (READ, GOTO,
SIN, etc.), whereas other data
areas are only ASCII strings of
error messages or floating point
representations such as pi. The
latter should be left alone,
whereas the former need to have
an offset applied to them so that
they will run properly.

With this last bit of informa-
tion, you can generate a new
BASIC by simply applying the
proper offset to the parts of the

program that need it. One way to
do this is to somehow write the
source listing to a disk file and
then reassemble it.

However, knowing which
areas need special treatment,
you can bypass the assembly
process and simply add the re-
quired offset where necessary.
This can be done in machine lan-
guage and would probably run
the fastest that way, but it can
also be done in BASIC using the
file-accessing commands avail-
able to take a copy of standard
BASIC located on a disk, pro-
cess it a little at a time in memo-
ry and write the relocated BASIC
to a new disk file. When you are
finished, this new file can be run
as BASIC at a new location in
memory and use either the
standard DOS or another DOS
that can also be relocated using
a similar procedure.

The Program

The program to relocate BA-
SIC is really quite simple. It is al-
so quite long because each time
a break occurs in the type of
code being relocated, a new
value must be assigned to Ml,
and a call to a subroutine must
be made. Loading and execut-
ing the program is direct and to
the point. When the program is
run, you will see that it asks for
some information with prompts.
Each time a prompt is printed
you can type a carriage return,
and the program will default to
certain values. For the number
of digits, the default is 8; for the
disk drives, it is drive #1; for the
starting address of BASIC, it is
2A00H; and for the DOS, it is
2000H.

I’ve tried to make it impossi-
ble (or at least difficult) to enter
parameters that wouldn’t make
sense, but it pays to show a little
caution anyway. Once the pro-
gram begins running, you might
as well go get yourself a cup of
coffee— or an entire meal if de-
sired. It takes about 30 minutes
to churn through the file.

Certain prerequisites are nec-
essary before running. The stan-
dard BASIC must be in a Type 1
file called “BASIC” for the
8-digit version, or “BASIC14” for
the extended precision version.
Also, the BASIC must be Re-
lease 4 for the program to work.

610 Ml=l 0766

620 GOSUB 3930

630 M 1=1 0769

640 GOSUB 4290

650 GOSUB 4350

660 GOSUB 4290

670 GOSUB 3930

680 Ml=10777

690 GOSUB 4290

700 Ml=10988

710 GOSUB 3880

720 Ml=11256

730 GOSUB 3880

740 Ml=l 1421

750 GOSUB 3930

760 Ml=11707

770 GOSUB 4290

780 Ml=12040

790 GOSUB 3880

800 Ml=12118

810 GOSUB 3880

820 M 1=1 21 53

830 GOSUB 3800

840 M1=12199

850 GOSUB 3800

860 M 1=1 221 6

870 GOSUB 3800

880 Ml=12278

890 GOSUB 3880

900 M 1=12291

910 GOSUB 3800

920 Ml=12311

930 GOSUB 3880

940 Ml=12319

950 GOSUB 3800

960 M 1=1 2324

970 GOSUB 3800

980 Ml=12329

990 GOSUB 3800

1000 M 1=12350

1010 GOSUB 3800

1020 M 1=1 2390

1030 GOSUB 3800

1040 Ml=l 2402

1050 GOSUB 3800

1060 Ml=l 2437

1070 GOSUB 3800

1080 Ml=l 2481

1090 GOSUB 3800

1100 Ml=l 2496

1110 GOSUB 3800

1120 GOSUB 3900

1130 M 1=1 251 9

1140 GOSUB 3880

1150 M 1=1 2565

1160 GOSUB 3880

1170 Ml=l 2671

1180 GOSUB 3800

1190 Ml=12814

1200 GOSUB 3880

1210 Ml=l 3065

1220 GOSUB 3880

1230 Ml=l 3098

1240 GOSUB 3880

1250 Ml=13134

1260 GOSUB 3880

1270 Ml=l 3278

1280 GOSUB 3880

1290 Ml=l 3319

1300 GOSUB 3880

1310 Ml=l 3387

1320 GOSUB 3880

1330 Ml-13406

1340 GOSUB 3880

1350 Ml=13434

1360 GOSUB 3880

1370 Ml=l 3676

1380 GOSUB 3880

1390 M 1=1 3747

1400 GOSUB 3880

1410 Ml=13807

1420 GOSUB 3880

1430 Ml=l 4027

1440 GOSUB 3880

1450 Ml=14040

1460 GOSUB 3880

1470 Ml=14103

1480 GOSUB 3880

1490 M 1=1 41 58

1500 GOSUB 3880

1510 Ml=l 4656

1520 GOSUB 3930

1530 Ml=14677

1540 GOSUB 4290

1550 Ml=l 4825

1560 GOSUB 3930

1570 0=-0

1580 GOSUB 3930

1590 0=-0

1600 Ml=l 5056

1610 GOSUB 3930

1620 IF B=1 4 THEN M=M-3

1630 M 1=1 51 09

1640 GOSUB 4290

1650 Ml=l 5131

1660 GOSUB 4350

1670 01=0

1680 0=N 1-8192

1690 GOSUB 4350
1700 0=01
1710 M 1=1 5205
1720 GOSUB 4350
1730 Ml=15620
1740 GOSUB 4290
1750 FOR 1=1 TO 8
1760 GOSUB 4290
1770 GOSUB 4350
1780 NEXT I
1790 Ml=15648
1800 GOSUB 4290
1810 GOSUB 4350
1820 FOR 1=1 TO 22
1830 GOSUB 4290
1840 GOSUB 4350
1850 NEXT I
1860 M 1=1 5792
1870 GOSUB 3880
1880 M 1=1 6061
1890 GOSUB 3880
1900 Ml=161 16
1910 GOSUB 3800
1920 M1=16131
1930 GOSUB 3880
1940 M 1=161 55
1950 GOSUB 3880
1960 Ml=16178
1970 GOSUB 3930
1980 IF B=1 4 THEN M=M-12
1990 M 1=1 61 98
2000 GOSUB 4290
2010 M1=16300
2020 GOSUB 3930
2030 IF B=1 4 THEN M=M-6
2040 Ml=l 6310
2050 GOSUB 4290
2060 Ml=l 6446
2070 GOSUB 3880
2080 M 1=1 6507
2090 GOSUB 3880
2100 Ml=16514
2110 GOSUB 3930
2120 IF B=1 4 THEN M=M-3
2130 Ml=16519
2140 GOSUB 4290
2150 Ml=l 6538
2160 GOSUB 3880
2170 M 1=1 6561
2180 GOSUB 3880
2190 Ml=16672
2200 GOSUB 3880
2210 M1=16683
2220 GOSUB 3880
2230 Ml=16696
2240 GOSUB 3800
2250 Ml=16763
2260 GOSUB 3880
2270 Ml=16795
2280 GOSUB 3880
2290 Ml=l 681 9
2300 GOSUB 3880
2310 M 1=1 6828
2320 GOSUB 3880
2330 Ml=16836
2340 GOSUB 3880
2350 M 1=1 6882
2360 GOSUB 3880
2370 M 1=1 690 3
2380 GOSUB 3880
2390 M 1=1 6959
2400 GOSUB 3880
•2410 Ml=16968
2420 GOSUB 3880
2430 Ml=17253
2440 GOSUB 3880
2450 M 1=1 7307
2460 GOSUB 3880
2470 Ml=17381
2480 GOSUB 3880
2490 Ml=17395
2500 GOSUB 3880
2510 Ml=17419
2520 GOSUB 3880
2530 Ml=17694
2540 GOSUB 3880
2550 Ml=17744
2560 GOSUB 3880
2570 M 1=1783 1
2580 GOSUB 3880
2590 Ml=17855
2600 GOSUB 3880
2610 Ml =179 20
2620 GOSUB 3880
2630 Ml=1793 3
2640 GOSUB 3880
2650 M 1=181 01
2660 GOSUB 3880
2670 Ml=181 05
2680 GOSUB 3880
2690 Ml=18219
2700 GOSUB 3880
2710 Ml=18237
2720 GOSUB 3930
2730 IF B=1 4 THEN M=M-3
2740 Ml=18242
2750 GOSUB 4290
2760 M 1=18327

Microcomputing January 1980 91

2770 GOSUB 3880

3600 M 1=23269

2780 M 1=1 83 56

3610 GOSUB 4290

2790 GOSUB 3880

3620 Ml=23387

2800 M 1=1 84 22

3630 GOSUB 3930

2810 GOSUB 3880

3640 IF B=1 4 THEN M=M-70

2820 Ml=18428

3650 M 1=23552

2830 GOSUB 3880

3660 GOSUB 4290

2840 Ml=l 84 34

3670 PRINT

2850 GOSUB 3880

3680 END

2860 Ml=18440

3690 REM SUBROUTINE TO CONVERT FROM HEX STRING TO DECIMAL

2870 GOSUB 3880

3700 N 1=0

2880 Ml=18446

3710 FOR 1=1 TO LEN (Q$ )

2890 GOSUB 3880

3720 Q=ASC(Q$(I,I))-48

2900 Ml=18485

3730 IF Q>=0 AND Q<=9 THEN 3760

2910 GOSUB 3800

3740 Q=Q-7

2920 Ml=l 8838

3750 IF Q<1 0 OR Q>15 THEN Nl=10000

2930 GOSUB 3800

3760 N 1=1 6*N 1+Q

2940 Ml=l 8889

3770 NEXT I

2950 GOSUB 3800

3780 RETURN

2960 M 1=1 91 57

3790 REM SUBROUTINE TO HANDLE DOS REFERENCES

2970 GOSUB 3880

3800 GOSUB 3930

2980 M 1=1 92 02

3810 01=0

2990 GOSUB 3880

3820 0=N 1-8192

3000 Ml=19528

3830 GOSUB 3930

3010 GOSUB 3880

3840 0=01

3020 M 1=1 9680

3850 RETURN

3030 GOSUB 3880

3860 REM SUBROUTINE TO RELOCATE INSTRUCTIONS FOLLOWED BY A

3040 Ml=20183

3870 REM 3-BYTE FIXED INSTRUCTION

3050 GOSUB 3880

3880 GOSUB 3930

3060 Ml=20928

3890 REM SUBROUTINE TO HANDLE 3-BYTE FIXED INSTRUCTIONS

3070 GOSUB 3880

3900 Q$="H H

3080 M 1=20972

3910 GOTO 3940

3090 GOSUB 3880

3920 REM SUBROUTINE FOR NORMAL INSTRUCTIONS

3100 Ml=21052

3930 Q$="L"

3110 GOSUB 3880

3940 READ #0,&X

3120 Ml=21 1 1 5

3950 WRITE # 1 , &X , NOENDMARK

3130 GOSUB 3880

3960 M =M+1

3140 Ml=21273

3970 REM FIND 3-BYTE INSTRUCTIONS

3150 GOSUB 3880

3980 IF X=1 95 OR X=205 THEN 4200

3160 M 1=21 31 1

3990 IF X=1 OR X=1 7 OR X=33 OR X=4 9 THEN 4200

3170 GOSUB 3800

4000 IF X=34 OR X=4 2 OR X=50 OR X=58 THEN 4200

3180 M 1=21344

4010 IF X=1 94 OR X=1 96 OR X=202 OR X=204 THEN 4200

3190 GOSUB 3880

4020 IF X=210 OR X=212 OR X=218 OR X=220 THEN 4200

3200 Ml=21412

4030 IF X=226 OR X=228 OR X=234 OR X=236 THEN 4200

3210 GOSUB 3880

4040 IF X=242 OR X=244 OR X=250 OR X=252 THEN 4200

3220 M 1=21440

4050 REM FIND 2-BYTE INSTRUCTIONS

3230 GOSUB 3880

4060 IF X=211 OR X=219 THEN 4150

3240 Ml=21472

4070 IF X=6 OR X=1 4 OR X=22 OR X=30 THEN 4150

3250 GOSUB 3880

4080 IF X=38 OR X=46 OR X=54 OR X=62 THEN 4150

3260 M 1=2 1 51 9

4090 IF X=1 98 OR X=206 OR X=214 OR X=222 THEN 4150

3270 GOSUB 3800

4100 IF X=230 OR X=2 38 OR X=246 OR X=254 THEN 4150

3280 Ml=21560

4110 REM ALL INSTRUCTIONS LEFT ARE 1 BYTE

3290 GOSUB 3880

4120 IF M<M1 THEN 3930

3300 Ml=21581

4130 RETURN

3310 GOSUB 3880

4140 REM 2-BYTE INSTRUCTIONS

3320 Ml=21604

4150 READ #0,&X

3330 GOSUB 3880

4160 WRITE #1,&X, NOENDMARK

3340 Ml=21642

4170 M=M+1

3350 GOSUB 3880

4180 GOTO 4120

3360 Ml=21657

4190 REM 3-BYTE INSTRUCTIONS

3370 GOSUB 3880

4200 READ #0 , &Y , &X

3380 Ml=21674

4210 IF Q$="H" THEN 4250

3390 GOSUB 3800

4220 Y=256*X+Y+0

3400 Ml=21680

4230 X=INT (Y/256)

3410 GOSUB 3800

4240 Y=Y-2 56*X

3420 Ml=21684

4250 WRITE #1 , &Y , &X , NOENDMARK

3430 GOSUB 3930

4260 M=M+2

3440 IF B=1 4 THEN M=M-27

4270 GOTO 4120

3450 Ml=224 50

4280 REM SUBROUTINE TO HANDLE BYTE DATA

3460 GOSUB 4290

4290 READ #0,&X

3470 Ml=22733

4300 WRITE #1,&X, NOENDMARK

3480 GOSUB 3930

4310 M=M+1

3490 IF B=1 4 THEN M=M-38

4320 IF M<M1 THEN 4290

3500 M 1=2 2783

4330 RETURN

3510 GOSUB 4290

4340 REM SUBROUTINE TO HANDLE WORD DATA

3520 Ml=22968

4350 READ #0,&Y,&X

3530 GOSUB 3930

4360 Y=256*X+Y+0

3540 IF B=1 4 THEN M=M-46

4370 X=INT (Y/256)

3550 Ml=23018

4380 Y=Y-2 56 *X

3560 GOSUB 4290

4390 WRITE #1 , &Y , &X , NOENDMARK

3570 Ml=23229

4400 M=M+2

3580 GOSUB 3930

4410 IF M<M1 THEN 4350

3590 IF B=1 4 THEN M=M-48

4420 RETURN

hand. One is to create a version
of BASIC that can be run at
3400H. The rationale behind this
is that if while you’re program-
ming, you suddenly run out of
disk space but have room on the
lower disk tracks, you have to
run COMPACT to open up some
space on the disk. Unfortunate-
ly, when this happens it uses a
scratch area of ten blocks im-
mediately following the DOS to
move files around. So, unless
you have yet another disk with
space on it to save your BASIC
program while COMPACT writes
all over the first part of BASIC,
you’re out of luck.

By putting BASIC at 3400H
you can run COMPACT (or use
the IN or DT commands in DOS)
without disturbing BASIC or its
program. Then you can reenter
BASIC from DOS and save the
program you’ve been working so
hard on before it evaporates. Of
course, you have to give up
about 2.5K of memory in BASIC
to do this, but these days memo-
ry seems to be becoming more
plentiful and less expensive,
and it need not be all that much
of a problem.

Another application is to relo-
cate both the DOS and BASIC to
run at the beginning of memory,
say with the DOS at 0000H and
BASIC immediately thereafter
(either with or without the ten-
block scratch area in between).
There are commercial programs
available for moving the DOS, so
I won’t discuss it here— except
to say you might want to try it
yourself to keep you out of trou-
ble on those rainy or snowy
afternoons. With a setup like
this, there’s no more fiddling
with DIP switches to change
those memory board addresses
when going from CP/M to North
Star and back.

The result of the program is a
file of the same length as the
standard version, and with a
name that includes the starting
address in it. The naming for-
mat is Bpp-xxxx, where pp is the
number of digits of precision (8
or 14) and xxxx is the hexa-
decimal starting address.

After completion, you must
assign the file a type of 1 and
give it a go-address (which will,
of course, be the same address

as that included in the name)
from DOS; there just isn’t any
convenient way to assign a go-
address from BASIC. Once this
is done you’re ready to test it
by typing GO B08-3400 (for ex-
ample). BASIC should load and
give its READY prompt. You can
then use MEMSET, if desired, to
allow more space for your pro-
grams commensurate with how
much memory you have avail-
able. Any programs written in

standard BASIC should be com-
patible with relocated versions
of same.

Many people don’t realize
that programs written in the
8-digit version can be run in the
14-digit version and vice versa,
but with a loss of precision. This
does not hold true of data files,
however, so don’t try it for those.

Uses

I can think of several uses off-

If you’re really handy at patch-
ing, you can write some short
routines to use the CP/M I/O
drivers with North Star BASIC.
The file-accessing patches are
much harder, but possible. With
just the I/O though, you can call
BASIC as a CP/M COM file and
at least write and run programs
even if you can’t save them. A
version of BASIC relocated to
0100H is the heart of this partic-
ular application. ■

92 Microcomputing January 1980

THE VERY BEST,

If you're serious about your TRS-80 computer, try these disk based
programs. When it comes to hardcore software, noboby does it like TBS.

BUSINESS MAIL SYSTEM by Dale Kuber is designed for large-
scale business users. Requiring 32K, two disks and printer, this
program will store up to 150,000 names in a single file spread
out over multiple disks. Each data disk holds 500 names. After data
entry, BMS automatically sorts the data by zip code and alphabetical
order within the zip code. The program tells you when and which data disk
to insert, expanding your files automatically until you've reached 300
disks. Data is input directly onto formatted screen display with the option
to use Company Name/ Attention instead of Last Name/First Name. Three
numeric and one alpha code fields are provided to help you use the search
and printout mode. BUSINESS MAIL SYSTEM allows you to program
the number and spacing of your labels and then print out and read your
data disks concurrently using accelerated printing. (This mode works only
with Centronics printers.) With more features than can be described here,
this high-powered program sells for $125.00.

ANALYSIS PAD by Del Jones is the epitome of first-class programming
in business applications. Requiring 48K, and one disk with a printer
recommended, this columnar calculator gives the user tremendous flexibil-
ity in data entry enabling the user to create 30 or more columns and rows.
Enter your own column and row labels. Enter your data by row or column
or directly onto screen display via edit mode. Move, swap, delete, and add
rows or columns. Create new pads by stripping relevant data from old files.
You never have to key in data twice. But more important than the powerful
data manipulation provided, you can add, subtract, multiply and divide one
column by another and put results in another column. You can perform up
to six calculations on one column and even define one column to be a
constant. The calculation routine you create can be saved and reused.

Print out the entire pad in four column segments to line or serial printer.
ANALYSIS PAD was originally advertised for 32K tape at $32.50. Since
then it has been totally rewritten and expanded to its present 48K disk
only form and sells for $49.50. It is easily worth twice as much. You have
to see it to believe it.

DATA MANAGER by Dale Kubler starts out where INFORMATION
SYSTEM leaves off. Requiring 32K and one disk, it accepts up to ten
user-defined fields with up to forty characters per field and 255 characters
per record. As with all TBS software, data entry and editing is professional
and simple to use. What makes this program stand apart from "in-mem’’
data managers is that it uses up to four disks on line as memory, or as
much as 320K of memory storage. Because disk sorts take more time than
in-mem sorts, DATA MANAGER enables the user to create and maintain

up to 5 “key" sort files for quick access of data. A utility program is pro-
vided to calculate the number of records possible since the amount of
records you can maintain is dependent on a number of variables. This pro-
gram also supports the upper/lower case modification, and printouts can
be programmed to almost any format and sent to line or serial printer. For
Centronic printers, accelerated printing is provided enabling the computer
to search and print at the same time. If you already have INFORMATION
SYSTEM, DATA MANGER will accept those files. (We are currently work-
ing on a program that will merge your data files with Electric Pencil files.)

A necessity for organized people, this program sells for $49.50.

CHECK REGISTER ACCOUNTING SYSTEM, adapted for the
TRS-80 by Dale Kubler and originally written by O.E. Dial, is the most
comprehensive check-balancing program written. Requiring 32K,two disks
and printer, this program does much more than just balance and reconcile
your checkbook. It enables you to define up to 60 account names and will
generate monthly summaries of all accounts with monthly and year-to-date
totals. Single-entry input allows the user to disperse one transaction over
several accounts and to make a 64-character note on each transaction.
Checks can be printed out after data has been entered. Aside from the
Statement of Accounts, CRAS also generates the following reports: Check
Register for any Month, Notes to Check Register, Income/Expense Distribu-
tion, Statement of Selected Accounts, Bank Reconcile Statement and
Suspense File. The Suspense file is an extra feature where you can make
notes to yourself for any month in the year. CRAS will make both you and
your accountant happy and it sells for $49.50.

TBS has other great software for your TRS-80. BASIC TOOLKIT,
SYSTEM DOCTOR & TERMINAL CONTROL are system utilities.
CHECKBOOK II, INFORMATION SYSTEM & EXERCISER are general
applications. Don’t forget the LIBRARY 100; 100 programs for only
$49 50 TBS also has DISK HEAD CLEANERS for TRS-80 and APPLE
and GRAN MASTER DISKETTES, the best on the market.

TBS is YOUR COMPANY, and to you we pledge to produce quality
software at a price you can afford. The above products are avaiable NOW
at Computer Stores and Associate Radio Shack Stores nationwide or
directly through us. For direct mail please include $2.00 for postage and
handling.

v 00 Reader Service — see page 227

Microcomputing January 1980 93

Bonaventura Paturzo
1929 Trudie Drive
San Pedro CA 90732

Synertek’s SYM-1:
Still Versatile

The ’nym’s new, but the SYM’s still the same good old VIM.

A bout 1 V 2 years ago, Syner-
tek Systems Corp. (PO Box
552, Santa Clara CA 95052) intro-
duced their Versatile Interface
Module (VIM). It’s now called the

SYM-1, but the versatile is still
included. It uses a 6502 micro-
processor that makes the SYM-1
a cousin of the KIM-1. The
SYM-1 includes an excellent 4K

system monitor (in ROM), and
the on-board 28-key keypad
(along with a 6-digit hex format
display) will get you started right
away into machine-language

programming (see Fig. 1).

SYM-1 Features

Before going into more detail
on the features of the system

-6 DIGIT HEX
DISPLAY

Fig. 1. Block diagram of the SYM-1 board (reprinted courtesy of Synertek Systems Corp.).

94 Microcomputing January 1980

The SYM-1 package.

monitor, let me skim over some
of the SYM-I’s features. The
board comes with IK of 2114-
type RAM and is expandable
(on-board) to a healthy 4K worth
of RAM. In addition to this,
decoding is provided to add
another 4K of RAM (off-board).

As mentioned before, the sys-
tem monitor resides in ROM, but
three sockets are provided to
add up to 24K bytes of addition-
al ROM/PROM. Addressing
jumpers are provided so that
each socket can accommodate
any of four different types of
read only memory devices.

On-board interfaces include a
cassette interface complete
with remote control (on/off of
cassette recorder motor) that is
usable in two modes: KIM-1
compatible and high speed
(nearly 1500 baud). A Model 33
Teletype can be added through
the 20 mA teleprinter interface,
or if you’d rather use an RS-232
CRT terminal, an interface is
provided for this also.

All of the software needed to
support the cassette, Teletype
and CRT terminal interfaces is
included in the system monitor.
In addition to this, the SYM-1
automatically adjusts for baud
rates from 300-4800 baud (inclu-
sive) when the CRT terminal in-
terface is used. For users with-
out terminals, the SYM-1 pro-
vides an oscilloscope driver that
will allow you to use an ordinary
oscilloscope to display one line
of 32 characters; the software
for this scope driver is included
in the SYM-1 reference manual.

For input/output and timing
applications, the board comes
with two 6522 VIAs (versatile
interface adapter) and one 6532
device. These three devices are
worthy of a chapter by them-
selves; they are one of the big
reasons the SYM-1 is so ver-
satile. The 6532 has an on-chip
programmable interval timer; its
I/O ports are used to interface
the keypad/display or any other
user-supplied terminal to the
microprocessor.

The 6522 devices include two
on-chip timers— an interval
timer (that can double as a
“pulse counter”) and a timer
that can operate either in a free-
running mode or in the
“interval” mode. The 6522s also

include two 8-bit bidirectional
I/O ports (with “handshake”
capability) that can be con-
figured in any I/O combination
through the 6522’s Data Direc-
tion registers. In fact, some of
the features of the SYM-1 (such
as the scope driver, cassette
interface and the write pro-
tection of user RAM) use part of
these VIAs.

If this I/O capability is not
enough for you, a socket is pro-
vided so you can add one more
6522 to the SYM-1 to give you 16
additional I/O lines (with hand-
shaking lines), plus the timers
and other on-chip functions.
Four buffers are also provided
on-board (on four I/O pins of VIA
#3) that the user can configure
in any way he chooses.

And there’s one nice thing
about the SYM-1 that I’ve saved
for now: It’s already assembled
and fully tested; all you add is a
single +5 V supply.

System Monitor

I left the discussion of the
system monitor for now be-
cause if you bought a micro-
computer to learn about it and
its microprocessor (as I did),
then you’ll want an operating
system that’s versatile and
thorough enough to allow you
debugging facilities and to give
you the ability to examine reg-
isters, move data around and so
on. It would take too much
space to describe each of the
system commands, so here is
just a list: Memory Ex-
amine/Modify, Memory Search,
Register Examine/Modify, Go (to
start the program at immediate
address or address given),
Verify (display eight bytes in
memory or any number of
bytes), Deposit To Memory,
Calculate (for hexadecimal
arithmetic), Move Memory Block
(to another location), Jump,
Store Double Byte, Fill Memory
Locations X-Y With Z, Write Pro-
tect (user RAM), Load Tape
(KIM-1 or high-speed), Load
Paper Tape, Save Paper Tape,
Save Tape (KIM-1 or high-speed)
and Execute.

In addition to these com-
mands, “ + ” advances eight
bytes (as when in Memory Ex-
amine), retreats eight

bytes, advances one byte

(or register) and retreats
one byte. There are eight user-
defined keys to enable you to
add to the monitor’s command
repertoire, and there is a system
reset key to allow you to sweep
your mistakes under the rug.
And, of course, there is the
DEBUG key/function.

Pressing DEBUG allows you
to single-step through each
instruction in your program.
Thus, after each instruction is
executed, you can examine all
of the registers and any memory
locations and then go on to the
next instruction in your program
by pressing GO and Carriage
Return (CR).

You can let the monitor step
through your program, but at a
rate that’s closer to jogging
rather than mile-a-minute sprint-
ing. By changing the “Trace”
velocity, you can set up the
monitor to display the Program
Counter address and the con-
tents of the accumulator, pause
and then resume execution,
again one instruction at a time.
And there is even a set of error
messages to tell you when
something is wrong (I still like
the Bronx cheer method better).

The error codes are inter-
active; that is, the error message
flashed onto SYM-1 ’s display
depends on the context in which
the error occurred. This simpli-
fies to a message of “Er XX,”
where XX is a two-digit repre-
sentation of the byte that
couldn’t be digested. Finally, for
you programmers, the eight
user-defined keys should start

you on your way to controlling
the world.

Unfortunately, I’ve had to
restrict (and sometimes omit)
the descriptions of the SYM-I’s
features and capabilities. For
more detail consult the compre-
hensive manuals that come with
the board.

Applications

With its I/O and timing capa-
bilities, the SYM-1 is an obvious
choice for intelligent-controller-
type applications. But the board
is an application in itself, teach-
ing you machine-language pro-
gramming and the merits of the
6502 microprocessor, including
the versatile combination of its
instruction set and addressing
capabilities. You can apply what
you learn to all microprocessor-
based computers, as all micro-
processors share common fea-
tures that will enable even a
novice to get his or her foot in
the door.

For those interested in pro-
gramming in a high-level lan-
guage, there is Synertek’s
BASIC, which is packaged in
two ROMs that plug right into
sockets provided on the SYM-1.
This extended BASIC even has
string functions that should en-
able you to write a nice text
editor or two.

But it is the SYM-I’s ability to
interface with the real world that
will please the utility-minded
user most. If he is a photog-
rapher, the SYM-1 can automate
his darkroom from enlarger tim-
ing to agitation of the chem-

Microcomputing January 1980 95

X

icals; if he is interested in an
audiovisual display, he can
control lighting systems to the
tune of his favorite music,
creating effects that will make
ordinary color-organs pale in
comparison.

To an experimenter/hobbyist,
the SYM-1 could combine
several test instruments into
one, such as a frequency
counter, digital voltmeter and a
programmable pulse generator;
for the electronic music en-
thusiast, the SYM-1 could

become the heart of a
polyphonic synthesizer, gen-
erating envelopes for your VCAs
(voltage controlled amplifier)
and even making sure you’re in
tune.

You can write programs that
will test ICs (with the addition of
some wire and a zero insertion
force socket or two), program
your EPROMs (and check for er-
rors), move "light” pieces on a
game board, secure your home;
in short, anything that can be
controlled electrically (directly

or indirectly) can most probably
be controlled and monitored by
SYM-1 . That includes the coffee-
pot.

My own uses for SYM-1 have
included some of the above
(such as the EPROM program-
mer) plus such things as a geo-
metric art generator that uses
an ordinary oscilloscope, and a
music program that will play up
to 256 notes (any audible fre-
quency) and uses the on-board
timers (in the VIAs) for the notes’
pitch and duration. When I got

the Synertek BASIC, I wrote
some “recreational” programs
including a conversational pro-
gram, and even a program that
will balance a checkbook.

So, if you like to program in
BASIC, or are interested in using
a microcomputer as the in-
telligent heart of any system
(from kitchens to multi-channel
data-acquisition systems), or if
you’re just interested in learning
about microprocessors and
microcomputers, look into the
SYM-1. ■

TRS-80 SOFTWARE TRS-80

Aardvark games are now available for
the TRS-80. Level II.

REAL TIM I

Starfighter $5.95

A real time space mission featuring 4 types of op-
ponents, working instruments, 3 types of weapons,
and 10 levels of difficulty.

Slashball $5.95

Once a machine code favorite, it's now available in
BASIC. It takes fast reflexes and planning to score.

Breakthru $5.95

This fast action, pinball-like game features user
selectable bumpers.

FOR THINKERS

Battlefleet $5.95

This one is Battleship all grown up for adults. A tough
thinker's game that you play against the computer.

All programs come on cassette with listings and
documentation.

Send $.25 or SASE AARDVARK

for descriptions. TECHNICAL

^A90 SERVICES

1690 BOLTON, WALLED LAKE
Ml <8088 313-624-6316

TRS-80

SPEEDUP MOD

REVERSE VIDEO

Install a Speedup Board
and run your Level II TRS-80 50% faster. Simple
“Out” statement changes between normal and
faster 2.66 mhz operation. No switch required -
no program crashes.

4 switch (not supplied) may be added tor manual control.

ASSEMBLED $24.95 Kit $18.95

REVERSE VIDEO without switches I
or software. It provides black characters and
graphics on a white screen for a crisper presen-
tation. Change between normal and reverse by
simultaneously pressing a combination of three
keys on the keyboard.

ASSEMBLED $14.95

California residents add 6% sales tax
For shipments outside of USA add 15%.

Bill Archbold Electronics

Dept KB, P.O. Box 7123, Sacramento, CA 95826
(916)362-3627 ^ MB

MEMOREX

Floppy Discs

Lowest prices. WE WILL NOT
BE UNDERSOLD!! Buy any

quantity 1-1000. Visa, Mastercharge
accepted Call free (800)235-4137
for prices and information. All
orders sent postage paid.

SBASIC

NEW revision 4.0 of SDASIC. All the feotures
of SDASIC (cose structure, procedures, etc.)
plus LINK stotement to copy externol
source files ot compile time, multiple state-
ments per line, and more. Compile time
performance hos been improved by 50 per-
cent. Available on CP/M* * disk and TRS-80*
diskette for $50, listing $35, manual $10.

9

313 Meadow Lane
Hastings, Michigan 49058
(616) 945-5334
(Dealer inquiries invited)

*CP/M and TRS-80 are trademarks of
Digital Research and Tandy Corp. ✓ Utt

✓ M67

CASSETTE

DUPLICATION

TRS-80 (I & II), PET, APPLE, KIM, ATARI

Quality software duplication is more
than copying cassettes. Microsette du-
plication uses a proprietary high speed
duplicator designed specifically for
computer program duplication. The fin-
ished products are of consistent quality,
guaranteed to load. Minimum order is
100 with discounts for higher quanti-
ties. Call (408) 735-8832 for details.

MICROSETTE CO.
777 Palomar Avenue
Sunnyvale, CA 94086

Canadian

8K MEMORY KITS

Ml — Fast Signetics 21L02-1 RAMs with 20
pages of Documentation— solder mask Low
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and Robinson Nugent 1C sockets only $199.95

MEM1— WAMECO bare board as used in
above kits $39.95

Write for info on WAMECO CPU and other
S-1 00 bare boards.

ART HON COMPUTER

A 9 A A ^ I04TH0N HOLDINGS LTD)

✓ 08

12411 Stony Plain Rd
Edmonton, Alberta Canada T5N3N3

96 Microcomputing January 1980

Computer Design Labs Z80 Di sk Softw are

We have acquired the rights to all TDL software (& hardware). TDL software has long had the reputation of being the best in the
industry. Computer Design Labs will continue to maintain, evolve and add to this superior line of quality software.

— Carl Galletti and Roger Amidon, owners.

All of the software below is available on
any of the following media for operation
with a Z80 CPU using the CP/M* or similar
type disk operating system (such as our
own TPM*).

for TRS-80* CP/M (Model One)
for 8" CP/M (soft sectored single density)
for 5V4" CP/M (soft sectored single density)
for 5 V 4 " North Star CP/M (single density)
for 5V4" North Star CP/M (double density)

BASIC I

A powerful and fast Z80 Basic interpreter
with EDIT, RENUMBER, TRACE, PRINT
USING, assembly language subroutine
CALL, LOADGO for “chaining”, COPY to
move text, EXCHANGE, KILL, LINE INPUT,
error intercept, sequential file handling in
both ASCII and binary formats, and much,
much more. It runs in a little over 12 Kand is
ROMable. An excellent choice for games
since the precision was limited to 7 digits in
order to make it one of the fastest around.
$69.95.

BASIC II

Basic I but with 1 2 digit precision to make
its power available to the business world
with only a slight sacrifice in speed. Still
runs faster than most other Basics (even
those with much less precision). $99.95

BUSINESS BASIC

The most powerful Basic for business
applications. It adds to Basic II with random
or sequential disk files in either fixed or
variable record lengths, simultaneous
access to multiple disk files, PRIVACY
command to prohibit user access to source
code, global editing, added math functions,
and disk file maintenance capability without
leaving Basic (list, rename, or delete).
$159.95.

ZEDIT

A character oriented text editor with 26
commands and “macro” capability for
stringing multiple commands together.
Included are bidirectional search with
optional replace and a complete array of
character move, add, delete, and display
functions. $49.95.

ZTEL

Z80 Text Editing Language - Not just a
text editor. Actually a language which allows
you to edit text and also write, save, and
recall programs which manipulate text.
Commands include conditional branching,
subroutine calls, iteration, block move,
expression evaluation, and much more.
Contains 36 value registers and 10 text
registers. Be creative! Manipulate text with
commands you write using Ztel. $68.95.

TOP

A Z80 Text Output Processor which will
do text formatting for manuals, documents,
and other word processing jobs. Works with
any text editor. Does justification, page
numbering and headings, spacing,
centering, and much more! $68 95
*Z80 is a trademark of Zilog
‘TRS-80 is a trademark of Radio Shack

MACRO I

A macro assembler which will generate
relocateable or absolute code for the 8080
or Z80 using standard Intel mnemonics plus
TDL/Z80 extensions. Functions include 14
conditionals, 16 listing controls, 54 pseudo-
ops, 11 arithmetic/logical operations, local
and global symbols, chaining files, linking
capability with optional linker., and
recursive / reiterative macros. This
assembler is so powerful you’ll think it is
doing all the work for you. It actually makes
assembly language programming much
less of an effort and more creative. $49.95

MACRO II

Expands upon Macro I’s linking
capability (which is useful but somewhat
limited) thereby being able to take full
advantage of the optional Linker. Also a
time and date function has been added and
the listing capability improved. $68.95

LINKER

How many times have you written the
same subroutine in each new program?Top
notch professional programmers compile a
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Linker to tie them together at assembly
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reduced and becomes comparable to
writing in a high level language but with all
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is compatible with Macro I & II as well as
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$68.95

DEBUG I

Many programmers give up on writing in
assembly language even though they know
their programs would be faster and more
powerful. To them assembly language
seems difficult to understand and follow, as
well as being a nightmare to debug. Well,
not with proper tools like Debug I. With
Debug I you can easilyfollowtheflowof any
Z80 or 8080 program. Trace the program
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the instruction executed and what it did. If
desired, modifications can then be made
before continuing. It’s all under your
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a subroutine call and up to seven break-
points can be set during execution. Use of
Debug I can pay for itself many times over
by saving you valuable debugging time.
$69.95.

DEBUG II

This is an expanded debugger which has
all of the features of Debug I plus many
more. You can “trap” (i.e. trace a program
until a set of register, flag, and/or memory
conditions occur). Also, instructions may
be entered and executed immediately. This
makes it easy to learn new instructions by
examining registers/memory before and
after. And a RADIX function allows chang-
ing between ASCII, binary, decimal, hex,
octal, signed decimal, or split octal. All

‘TPM is a trademark of Computer Design Labs It is not
CP/M* *CP/M is a trademark of Digital Research

these features and more add up to give you
a very powerful development tool. Both
Debug I and II must run on a Z80 but will
debug both Z80 and 8080 code. $88.95.

ZAPPLE

A Z80 executive and debug monitor.
Capable of search, ASCII put and display,
read and write to I/O ports, hex math, break-
point, execute, move, fill, display, read and
write in Intel or vinary format tape, and
more! Disk $19.95. Also available in 2Kx8
ROM with initialization for the SMB I or II
(3 ACIA’s and 1 PIA) $34.95.

SMB II bare board $49.95.

One PIA and four 74LS244’s for SMB II

$12.95

8080 version of Zapple - disk $19.95
on 2516 $49.95

TPM*

A NEW Z80 disk operation system! This
is not CP/M*. It’s better! You can still run
any program which runs with CP/M* but
unlike CP/M* this operating system was
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full advantage of its extra powerful instruc-
tion set. In other words its not warmed over
8080 code! Available for TRS-80*, Tarbell,
ICOM, Xitan DDDC, SD Sales “VERSA-
FLOPPY”, North Star (SD&DD), and Digital
(Micro) Systems. $49.95.

PAYROLL

The Osborne package. Requires C Basic 2
2 disks $74.95 Book $15.00

ACCTS REC/ACCTS PAY

By Osborne. Requires C Basic 2 $99.95
Book $15.00.

GENERAL LEDGER

By Osborne. Requires C Basic 2 $99.95
Book $15.00

C BASIC 2

Required for Osborene software $99.95
Manual included.

ORDERING INFORMATION

Visa, Master Charge and C.O.D. O.K. To
order call or write with the following infor-
mation.

1. Name of Product (e g. Macro I)

2. Media (e.g. 8” CP/M)

3. Price and method of payment (e.g.
C.O.D.) include credit card info, if
applicable.

4. Name, Address and Phone number.

5. For TPM orders only: Indicate if for
TRS 80, Tarbell, Xitan DDDC, SD Sales
(5V4” or 8”), ICOM (5V4" or 8”), North
Star (single or double density)or Di-
gital (Micro) Systems.

6. N.J. residents add 5% sales tax.

For Phone orders only call toll free
1-800-327-9191 Ext. 676

(Except Florida)

1-800-432-7999 Ext. 676 (Florida)

Computer Design Labs

342 Columbus Avenue
Trenton, N.J. 08629

Dealer inquiries invited.

^C156

For tech calls United Software Applications 609-599-2146 or Otto Electronics 609-448-9165

y* Reader Service — see page 227

Microcomputing January 1980 97

Converting Selectric Keyboards
from BCD to Correspondence Code

Part 2 of this article plugs into the electrical aspects of converting BCD Selectrics.

Robert M. Weil

1700 Security Pacific Plaza

1200 3rd Ave.

San Diego CA 92101

T he electrical part of the
modification consists of re-
wiring the contacts in the ma-
chine to bring out the addition-
al character selection informa-
tion made possible by use of
the Correspondence code.
There are three sets of trans-
mitting contacts. One set of
seven pairs is operated by the
selector bails to reproduce the
six-bit plus parity character se-
lection code. A second set con-
sists of five pairs operated by
the five machine control, or op-
erational, keys. Finally, a set of
shift transmit contacts senses
whether the mechanism is
being shifted, and whether to
uppercase or lowercase.

To generate codes for a full
character set, the shift informa-
tion must be stored and used
as a seventh character selec-
tion bit, doubling the number of
possible code combinations.

The use of the character se-
lection contacts is completely
straightforward. The code from
the interposers is reproduced
as contact closures and may be
directly connected to logic out-
side the machine. Application
of the operational and shift con-
tacts requires some explana-
tion, however.

Qty.

6
10
10

Operational and Shift Contacts

First, consider the operation-
al contacts. There is a contact
pair corresponding to each op-
erational function, which pro-
duces an inefficient 1-out-of-5
code. My original intention was
to convert this into binary form
and to combine the encoded
operational information with
the character selection code so
that both character and control
codes would appear on the
same output connections, as is
the case with ASCII-coded de-
vices. After considerable inves-
tigation, I concluded that a sim-
pler, more widely usable modifi-
cation would result if the ma-
chine were simply rewired to
IBM’s standard for Correspon-
dence-coded Selectric I/O’s.

Their approach is to just
bring the individual operational
contacts out to the connector.
This has two advantages. First,
it is easy to do. Second, it al-
lows the user to choose either a
hardware or a software method
of code conversion. A parallel
input port could be used to
monitor the status of the opera-
tional contacts, with a brief
lookup table provided to trans-
late contact closures into ASCII
control codes. Hardware meth-
ods would be more elaborate.
An interface with hardware
code conversion and hand-
shaking is in the planning

stages, and might be the sub-
ject of a future article.

The shift transmit contacts,
like the operational contacts,
would be combined in some
manner with the character se-
lection contacts if we intended
to put the complete code on a
limited number of output lines.
As in the case of the operation-
al contacts, I decided instead
to do it IBM’s way and bring
them out individually to the
connector.

In BCD machines, because
there are fewer codes, IBM
found it convenient to take the
opposite approach, combining
operational codes with charac-
ter codes. This was done by re-
coding the operational and
shift contact closures into
binary form using diodes and
connecting them to the charac-
ter selection contacts.

To complete modification to
Correspondence code, this in-
terconnecting wiring and the di-
odes must be removed. Modify-
ing the wiring is simplified
somewhat by IBM’s use of
taper pins, replaceable connec-
tor pins and, on some models,
wire-wrap clips for making con-
nections. What follows is a de-
tailed description of the re-
wiring required.

Connector Pin

r
s
t
u
v
w

X

Rewiring

Fig. 1 is the schematic of a
BCD machine. Note the manner
in which the character selec-
tion and operational contacts
are interconnected. Fig. 2 is a
complete schematic of Corre-
spondence-coded I/O wiring.
Figs. 1 and 2 are all-inclusive;
IBM states that there are prob-
ably no machines that include
all the features shown. My ma-
chine did not include a shift
magnet or shift mode contacts,
though it had shift transmit
contacts and a set called C3,
which, like shift mode, is a
part of the printer handshake
for shifting.

In both the Correspondence
and BCD versions, the six code
bits and the parity bit are
brought out to pins r, s, t, u, v, w
and x of the 50-pin connector.
(If you have one of the few
34-pin units, an unofficial
schematic is available from the
author. Send a stamped, self-
addressed envelope.) The cir-
cles marked with a lowercase
letter and a number refer to ter-
minals on the taper pin blocks.

Fig. 3a shows the layout of a
typical taper pin block; Fig. 3b
shows where the blocks are lo-
cated. Note that the operation-
al and shift mode contacts do

Connect To

a2
a4

a6 (no change)

Part No.

Price

2122258

Male pin (for 50-pin connector)

.80

4187243

Taper terminal (also 0187243)

.02

1166039

Slip terminal (wire-wrap clip)

.03

Parts list.

Remove From

a3
a2
a6

a4 a8

b3 b2

b5 b4

b6 b7

Table 1.

98 Microcomputing January 1980

not have their own outside con-
nections in the BCD machine.
They are connected to pins z,
AA, BB, CC, DD, EE and FF in
the Correspondence-coded ver-
sion. These pins are omitted
from the connector in the BCD
machine. These connector
pins, as well as taper pins and
wire-wrap clips, may be pur-
chased from any IBM parts out-
let. They are also sold by AMP,
Inc., but are difficult to pur-
chase in small quantities from
that source.

A list of the parts you will
need is included in the article.
Tools required are a soldering
iron, needle-nose pliers, cut-
ters, wire-strippers, a small and
a medium screwdriver and a
solder wick or solder-sucker.
Take a good look at the under-
side of your Selectric, and lo-
cate the features shown in Fig.
3b. Now you are ready to begin.

Procedure

1. Locate the character se-
lection contact assembly. It is
halfway back on the left, under
a clear plastic cover.

2. Remove the plastic cover.
Replace the two screws. They
will serve as guides for dress-
ing wires to clear the cover.

3. Examine the configura-
tion of the contacts. Notice
that they are arranged in seven
groups, each consisting of four
single-pole, double-throw sets.
This modification involves only
those farthest from the frame.
Those closest to the frame are
wired to form a parity tree. You
will not use it, but it is unneces-
sary to spend time removing
the wiring.

4. Unsolder all the wiring
from the lower contacts. In-
cluded will beonejumpertothe
right-hand upper set, which
should be unsoldered at both
ends. *

5. Using a needle-nose pliers,
disconnect allxliodes from the
taper pin blocks. Taper pins
can be disconnected by a sharp
pull straight out from the block.

6. After removal of the di-
odes, there will be seven taper
pins left with hookup wire at-
tached which was previously
unsoldered during step 4. Re-
locate these in the following
positions: a2, a4, a6, a8, b2, b4,

b7. Move the two pins already in
b7 to b8. If there was already a
pin in a2, remove it and tie it
back.

7. Refer to Fig. 4. Install a

piece of bus wire, tying together
all the center contacts of the
lower set, and connect it to the
right hand upper set as shown.
Loop the wire so that it clears

the cover screws by 1/8 inch or
more.

8. Connect the seven jump-
ers referred to in step 6 as
shown in Fig. 4.

50 POSITION AMP CONNECTOR NOTE [j]

(T)S0UARE0 LETTERS ARE PIN
CONNECTIONS AS SEEN FROM
OUTSIDE OF CONNECTOR

(I]MAGNET ARC SUPPRESSION
DIODE POLARITY AS SHOWN IS
STANDARD REVERSED POLARITY
IS OPTIONAL. CHECK MACHINE
WIRING TO DETERMINE
ACTUAL POLARITY.

Fig. 1. Schematic, BCD machine.

Microcomputing January 1980 99

9. Relocate the wires that
run from the connector to the
taper pin blocks as shown in

Table 1.

10. Any taper pins not dis-
posed of in steps 6 and 9 are

part of the interconnect from
the operational and shift con-
tacts. Disconnect them. If you

50 POSITION AMP CONNECTOR NOTE (T]

NOTES:

rn SQUARED LETTERS ARE PIN
CONNECTIONS AS SEEN FROM
0UTSI0E OF CONNECTOR

[ J\ MAGNET ARC SUPPRESSION
DIODE POLARITY IS STANDARD.
REVERSED POLARITY IS
OPTIONAL. CHECK MACHINE
WIRING TO DETERMINE
ACTUAL POLARITY.

Fig. 2. Schematic, Correspondence machine.

are accustomed to working
with either lacing cord or cable
ties, the main harness may be
unlaced between blocks A and
B and the operational contacts,
and the unnecessary wires re-
moved. If this seems too diffi-
cult, they may be tied back to
the harness. In either case,
double-check that you haven’t
removed a necessary wire. This
completes the rewiring of the
character selection contacts.

11. Looking at the bottom of
the machine, locate the opera-
tional contact assembly at the
lower right. The earliest models
had leaf-type contacts with
soldered connections. The vast
majority had a molded contact
housing with wire-wrap pins
protruding from the bottom.

12. Strip all wiring from the
operational contacts. Locate
and mark the wire that comes
from the normally open contact
of the C5 set. The C5 and C6
contacts are above the frame at
the rear of the mechanism, with
the C5 set closest to the motor.
Double-check that C5’s normal-
ly open contact is connected to
pin b of the connector.

13. Make a “daisy chain” of
wire-wrap clips with about 1
inch of hookup wire between
them. Slip the clips over pin J of
each set of contacts. Refer to
Fig. 5.

14. Connect the previously
identified wire from pin b onto
any of the “J” pins.

15. Measure the length of
wire required to reach from the
operational contact assembly,
pin L, to the connector.

16. Prepare five jumpers of
the appropriate length, each
with a male connector pin on
one end and a wire-wrap clip on
the other end.

17. Snap a connector pin
into position z of the connector.
Slip the wire-wrap clip over pin
L of the tab contacts. In the
same manner, connect pin AA
to space, pin BB to back space,
CC to return and DD to index.

18. Locate the shift transmit
contacts. Do this by switching
on your machine and looking at
its right side. Shift to upper-
case, then back to lowercase.
Note that on the end of a shaft
there is a round assembly that
rotates during a shift but is sta-

100 Microcomputing January 1980

CLEAR SCREW

Fig 4. Character selection contacts.

tionary otherwise. This is called
the shift clutch. Below and to
the rear of the shift clutch are
some contacts. Note that they
move during a shift. The rear-
ward group consists of three
sets of single-pole, double-
throw contacts. These are the
shift transmit contacts. Note

12 3 4 5 6 7 8

o o o o

o o o o

o o o o

o o o o

o o o o

o o o o

Fig. 3a. A typical taper pin
block. The three connections
under each number are con-
nected together internally.

v* Reader Service— see page 227

that there is a common connec-
tion to the swinging contacts of
all three pairs.

19. Disconnect and tie back
or remove all the wires con-
nected to the shift transmit
contacts.

20. Measure the length re-
quired to reach from the shift
transmit common to one of the
“J” pins on the operational
contact assembly. Prepare a
jumper with a wire-wrap clip at
one end. Solder it to the shift
transmit swinging contact
common, and connect the
other end tooneof the“J” pins.

21. Measure the length re-
quired to reach from the shift
transmit stationary contacts to
the 50-pin connector. Prepare

two jumpers, each with a con-
nector pin at one end.

22. Connect one jumper to
an inboard (toward the frame)
stationary contact. Snap the
connector pin into position EE
of the connector. Connect the
other jumper to an outboard
stationary contact. Snap its
connector pin into position FF
of the connector.

Modification Complete

This completes the modifica-
tion. You are now the owner of a
Correspondence-coded Selec-
tric I/O typewriter. It will serve
as a top-quality typewriter
using any Correspondence
typeball, and the electrical out-
put of the keyboard is now Cor-
respondence coded. You may
take either of two approaches
to interfacing the machine with
your computer. It can be done
entirely by using software, by

TAB SP BS CR INO

Fig. 5. Wire-wrap pins on oper-
ational contact assembly.

providing code conversion
lookup tables in memory. If a
hardware approach appeals to
you, there is a code conversion
1C, from ASCII to Selectric and
from Selectric to ASCII, avail-
able at a reasonable price
(MCM6561, available from Tri-
Tek, Inc.). Whichever method
you use, this modification will
transform your Selectric I/O
from a printer with a useless
keyboard into a fully functional
hard-copy terminal.*

Fig. 3b. Locations of contact assemblies and taper pin blocks on
bottom of machine.

IBM No. 241-5737-0
241-5990-0
241-5188-9

Service Manual $7.85

Adjustment Parts Manual 4.10

Part Number/Price List .45

Recommended reading.

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• GRAPHIC CHARACTERS GENERATED FROM KEY-
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• TRANSMIT SCREEN. PRINT SCREEN

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UNDER DOS A t7Q QC

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Microcomputing January 1980 101

Plucking Programs
from Thin Air

Amateur radioteletype transmissions are an unusual source of new programs. Eavesdrop-
ping can be easy with a properly programmed 6800 .

John J. Glidewell
3623 Charlene Dr.
Dayton OH 45432

P rograms from thin air? Yes.

By radioteletype. Radio-
teletype (RTTY) is used by many
amateur radio operators (hams)
to exchange messages and
other types of data. Such trans-
missions are usually printed on
a regular Teletype machine or
on a video display. Many hams
are also computer hobbyists,
and program exchange by RTTY
has become quite common.

Although you must be a li-
censed ham to transmit pro-
grams, anyone can receive
them. Long-range transmis-
sions use high-frequency (HF)
radio, but two-meter FM radio
(144.5-148 MHz) is being used
more frequently for exchange
of programs within the local
area. Reception of these trans-
missions is the subject of this
article.

Radioteletype

RTTY is accomplished by us-
ing two audio tones in exactly
the same manner as is done by
many computer tape systems.
The common standard defines
a mark as 2125 Hz and a space
as either 2295 Hz (narrow shift)

or 2975 Hz (wide shift). Narrow
shift is normally used on the
long-range HF bands, while
wide shift is more common on
the VHF bands. However, nar-
row shift is used locally on two-
meter FM; therefore, the listed
program will operate with
either.

The various means by which
transmission is accomplished
are not germane to the immedi-
ate problem; however, a brief
description of how RTTY recep-
tion and detection is accom-
plished is needed.

Output of a receiver tuned to
an RTTY signal is the pair of
audio tones. The tones are fed
into a device called a terminal
unit, or TU for short. The TU
may contain amplifiers and lim-
iters and a pair of narrow band-
width audio filters, one tuned to
each of the two audio tones.

The filters provide noise re-
jection and detection of the sig-
nal as either a mark or space.
The output of the filters actu-
ates a relay or some form of
SPDT switch, one position of
which represents the mark and
the other position the space.
The switch controls a standard
60 or 20 mA current loop to
drive the printer directly. Thus,
the TU acts like a computer I/O
device and could replace a key-

board or other input device to
enter data directly into the
computer.

On the noisy HF bands, a fair-
ly high-quality receiver and TU
are needed for good perfor-
mance. However, operation on
the two-meter FM band has a
couple of advantages. First, un-
like most HF operations, the
mark and space tones modu-
late the transmitter in such a
manner that they will be repro-
duced correctly by the receiver
even though it may be slightly
off frequency, provided only
that the signal remains within
the passband of the receiver.
Therefore, the highly stable re-
ceiver required on the HF
bands is not mandatory with
FM; although, of course, the
better the receiver, the better
the performance.

Second, FM reception is
much more free of noise as
long as a reasonable signal is
received. These two items per-
mit the elimination of the ex-
pensive TU and permit decod-
ing of the mark-space tones to
be done in software. The I/O in-
terface device described here is
simple and inexpensive, so the
only item of any expense re-
quired for two-meter FM RTTY
reception is a receiver, and you
may already have a suitable

one (more on that later).

At the time this is being writ-
ten, amateur RTTY is restricted
by the FCC to five-level Baudot
code. I hope that ASCII will be
approved soon since it is a far
more satisfactory code for
computer use. When ASCII is
approved, I have a similar pro-
gram all tested and ready to go.
In the meantime, Baudot is the
thing.

Even when ASCII is approved,
I believe Baudot will still be ex-
tensively used because of the
tremendous investment in ter-
minal equipment. Even if the
switch is made to ASCII for pro-
gram transmission, there will
still be a lot of interesting
things going on in Baudot, one
of which is called RTTY art in
which pictures are transmitted.
Last season I copied many nice
Christmas pictures and posters
using the program described.

Baudot in Miniature

Baudot consists of a start
bit, five data bits and a stop bit.
The five data bits are used to
represent all 57 characters.
Each code can represent either
of two characters, a letter or a
figure. The printer is told which
of the two possible characters
to print by a special shift code
that is transmitted preceding

102 Microcomputing January 1980

each string of characters of the
same type. Carriage return, line
feed and space, as well as the
two shift codes, are common to
both shift positions. If you are
interested in a more detailed
description of Baudot, as well
as a listing of the codes, I refer
you to the article by Haglund
and Reed (“Baudot Interface
Cookbook,” Kilobaud , Septem-
ber 1978, p. 66).

How It Works

The program listing was writ-
ten specifically for the SWTP
6800 computer but should run
on any 6800 machine provided
I/O and monitor addresses are
compatible or changed as nec-
essary. The technique used,
however, should be applicable
to any computer, and I have in-
cluded a flowchart of the main
part of the program, as well as a
detailed description, to permit
a similar program to be written
for other computers (see Fig. 1).

I will describe the first part of
the program, Initialize Pointers,
only briefly since it is unique to
the 6800. Basically, this portion
reads the program start ad-
dress from memory and uses
this data to find the location in
memory of the various tables
and messages. This was done
solely to make the program re-
locatable and can be dispensed
with if you want to use a fixed
address. The program, as writ-
ten, can be loaded anywhere as
long as the LSB of the address
is 00. The next program section
merely programs the output
ACIA to operate the printer.

The third section, Set Operat-
ing Parameters, provides flex-
ibility by permitting the user to
choose between several op-
tions. As mentioned earlier, the
decode portion of the program
will operate with either wide or
narrow shift. This is accom-
plished by loading MODSPC
with the appropriate value in
accordance with the user’s in-
put.

Most Baudot transmission is
at 60 wpm, although 100 wpm is
increasing. Seventy-five wpm is
more rare. The program permits
these three-speed options by
adjusting DELAY 1 and DELAY2,
which provide the appropriate
baud rate timing in the comput-

Fig. 1. Main program flowchart (continued on next page).

er. If your computer has baud
rate signals of the proper val-
ues accessible in software,
then you might want to make
use of these.

The flowchart commences
with the signal decode portion
of the program. RTTY tones, in
the form of square waves from
the interface, are fed into a de-
vice on my computer called a
control interface. This device is
used to input serial data, al-
though it is actually a parallel
port— the serial-to-parallel con-
version is in software. Input is
fed to the high-order bit of the
parallel port. By a shift-left in-
struction, the data is shifted in-
to the carry register, which is
queried to determine whether
the input is high or low. Other
machines can adopt their own
methods of obtaining the same
information.

With no signal input to the in-
terface, the computer data bit
will be high. The program re-
mains in the top loop until an
RTTY signal is detected by the in-
put bit going low. Upon detec-
tion of the low, the program
again loops in order to discard
the first cycle of tone data which
could be only a partial cycle.

Signal decoding actually
starts at the label HRPT. A time
counter, used to decode marks
and spaces, is cleared, and an
outer loop counter is set at six.
The high- and low-signal loops
operate as before, except now
a counter is incremented on
each cycle through the loop.
Six complete cycles of the RTTY
tone are counted to improve ac-
curacy. I selected six cycles as
a compromise between decode
accuracy and the need to de-
tect the beginning of a start bit
for baud timing.

The two RTTY audio tones
have different periods resulting
in different time counts for a
mark or space. Upon returning
to the main program, the time
count is compared with MOD-
SPC. If the count is less than
MODSPC, the signal is a space,
or start bit. If not, the program
loops back for another look.
Transition between marking
and a start bit can occur
anytime, even during the mid-
dle of the six cycles counted.
Therefore, DECODE is again
entered for a confirming look.

With start bit received, the
program clears a register to re-
ceive the incoming data and

sets a counter to keep track of
the five data bits. At 60 wpm
each bit is 22 milliseconds long,
and sampling should be done
near the center. Therefore, the
program must mark time from
near the beginning of the start
bit to the center of the first data
bit. DELAY1 provides this. At
the label NEXT, DECODE is en-
tered five times. After each re-
turn, MODSPC is checked for
mark or space, or, as I have la-
beled them, a one or zero. The
appropriate bit is then shifted
into the data storage register.
After each bit a delay of slightly
less than 22 msec is introduced
by DELAY2.

Subroutine OUTDAT trans-
lates from Baudot to ASCII,
prints the data and stores the
data in memory. OUTDAT
checks the data for a carriage
return, line feed or space and
generates the appropriate ASCII
form. If the code is none of
these, the program will look for
a figure or letters shift and store
the appropriate shift data. Shift
information is not stored in
memory, only ASCII data. Any
remaining characters are data.

The array TABLE contains
the ASCII codes arranged in the

Microcomputing January 1980 103

Fig. 1. ( continued ).

order of the corresponding
Baudot code set. The input
Baudot code itself then be-
comes the least significant half
of the array pointer. The first 20
hex positions in TABLE contain
ASCII letters, and the next 20
hex spaces contain the figures.

If the figures shift code has
been received, a 20 hex will be
stored in SHIFT and added to
the pointer. If TABLE started at
location XX00, then nothing
more would be required. How-
ever, I loaded TABLE immedi-
ately following the program to
save space. The actual location
is found by adding an OFFSET
to the Baudot code in addition
to SHIFT.

The program uses the con-
vention that reception of a
space anywhere in the text will
cause an automatic shift to
Baudot letters mode, regard-
less of which shift was in use
before (downshift on space).
Upon receipt of a space, SHIFT
is cleared to set letters mode.

Operation

In operation, the receiver is
connected via its earphone or

external speaker jack to the in-
put of the interface. If your re-
ceiver connection mutes the in-
ternal speaker, you may want to
add some sort of monitor
across the line so you can hear
the input signal. It is helpful if
you can observe the output of
the interface on a scope while
adjusting radio volume and in-
put gain control of the inter-
face. You want to get an output
that looks as clean as possible
with little jitter. Don’t mistake
mark-space shifts as jitter. I
have found best results with my
particular system with receiver
audio set near maximum and
interface gain reduced to about
the center of the control.

Before entering the program,
be sure to load A048-49 with
program start address, even if
your monitor does not require
it. On going to the program, you
will be asked to enter wide or
narrow shift, speed and save
data option.

One caution: If you elect to
save the data in memory, don’t
forget to enter memory storage
address range into A002-A005
before going to the program;

otherwise, you can wipe out
your program. I know! Remem-
ber Glidewell’s law: The more
stupid the mistake, the longer it
takes to find.

Once the specified field is
filled, the program will halt, so
give it enough room. The printer
should now start printing.

I/O Interface

The interface circuit is
shown in Fig. 2. The circuit is
built around the same interface
used for the tape recording sys-
temin my article, “6800 Tape
System’’ ( Kilobaud Microcom-
puting , December 1979, p. 78),

00*7 20K

1

6

/4-3900

rv.

1

except the 7400 NAND gate has
been replaced with a 74132
Schmitt trigger. The original cir-
cuit worked fine with narrow
shift RTTY; however, when I
went to wide shift, problems de-
veloped. These were caused by
the limited audio bandwidth of
the communications receiver
that attenuated the high 2975
Hz tone. The 7900 op amp was
added to provide some gain
and limiting. Output of the 7900
is a chopped-off sine wave
that is further squared in the
74132.

With no input signal, the out-
put of the op amp is low. Since
the RS-232 input on MP-C re-
quires a low for no signal if the
20 mA loop section is being
used, two sections of the 74132
are used to maintain the proper
conditions.

If you are using only the 20
mA loop portion of the control
interface, the circuit is con-
nected directly to MP-C as
shown in Fig. 2. Remove the
ground strap from terminal Rl
and connect the interface di-
rectly in its place. Your system
should work normally with no
interaction between the two in-
puts on MP-C. If you are already
using the RS-232 input (termi-
nal Rl) for another terminal, an
SPDT switch, as indicated in
Fig. 2 by the dashed lines,
should be installed. After ini-
tializing the program, simply
switch to the RTTY position.

The circuit is built on a two-
IC board from Radio Shack
(276-024). The cabinet is also
from Radio Shack. Other parts
came mostly from the junk box.
I built a power supply in one of
my duller moments. Current
drain is so low, the 5 volts re-
quired could just as easily have

VIDEO

TERMINAL

1/4 1/4

1/4-3900 74|32 77,32

+ 5V - PIN 14 BOTH ICs
GND - PIN 7 BOTH ICs

r

4 RI
MP-C
GND

Fig. 2. The input interface circuit. The dashed lines are for an alter-
nate connection if you already have another terminal connected to
terminal Rl on MP-C.

104 Microcomputing January 1980

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Microcomputing January 1980 105

come from the computer I/O
board. I use this same circuit for
the tape system previously
referenced; hence I incorpo-
rated a switch and extra jacks
for this function. Also included
on my board is an interface for
transmission of RTTY using
computer-generated tones.

Modifications

The program listing contains
delay values to suit the original
SWTP 6800. The 68/2 has a dif-
ferent clock circuit that runs
around one MHz, so certain tim-
ing changes are required. These
changes are listed in Table 1.
The 68/2 does not use a crystal
clock and may be subject to
some drift. Since timing is fairly
critical, particularly in DECODE,
you should make sure you stay
as close to one MHz as possible.

If you are writing a program
for another computer, you will
have to compute your own de-
lays. The required values for
MODSPC can either be com-
puted or found by experiment-
ing. In this latter case, it helps

to make a tape recording of
each of the two (or three) audio
tones. Play these tones into
your version of DECODE and
store the time count obtained
after each sequence of six cy-
cles. An examination of the re-
sults should provide a value for
MODSPC. Select a point mid-
way between the mark and
space counts.

The program listing accepts
input from a PIA on I/O board
MP-C, but you can use a PIA in
any I/O slot. To do this, one of
the unused sections of the
74132 in Fig. 2 is added to the
circuit in accordance with Fig.
3. You will have to change line
430 in the program listing to the
address of the PIA. The extra
program steps listed in Fig. 4
should be added to program the
PIA as an input. Lines 1290 and
1300 of the original program
can now be deleted as they are
only used with the MP-C.

Output of the program is
through a serial ACIA located in
I/O slot three. Do not try to use
the MP-C for output; it will not

1/4

74132

Fig. 3. Alternate connection
for input to a PIA located in an
I/O slot other than the control
port.

work. Otherwise, either serial or
parallel output can be used. For
an ACIA, change line 470, PRT-
DAT, to the appropriate ad-
dress. If you plan to use a paral-
lel port, the I/O routines in the
program will have to be changed
accordingly.

If your printer is connected to
an ACIA in the control port, I/O
slot one, you have two choices.
You can use the I/O routine in
the program by changing line
470 to $8004 or you can use
your monitor I/O routines with
proper calls. One caution: us-
ing the monitor may cause trou-
ble for a 110 baud printer when
receiving at 100 wpm, particu-
larly if your system has the
1.7971 MHz baud rate crystal.

Line No.

Change

0910

LDA A #$AC

0980

LDA A #$C2

1000

LDX #$0D4F

1020

LDX #$094 E

1110

LDX #$0715

1130

LDX #$0527

1160

LDX #$0A6B

1180

LDX #$075A

Table 1. Program changes

necessary

with a 1 MHz

clock. These are computed

values, but should work.

The baud rate generated is
slightly low, and your printer
may occasionally get behind
when copying a slightly fast
transmission. Programming the
ACIA for one stop bit avoids
this. For printers with faster
baud rates there will be no
problem.

Receivers

You will need a two-meter
(144.5-148 MHz) FM receiver.
The first choice is a regular
amateur receiver. Kits for five-

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106 Microcomputing January 1980

Microcomputing January 1980 107

00670

6920

96

FF

LDA

A

TEMP3+ 1

006S0

6922

97

EF

STA

A

MSG22+ 1

00690

'6924

CE

6B1 4

LDX

#MSG3

00700

.6927

DF

FE

STX

TEMP3

007 1 0

6929

96

FF

LDA

A

TEMP3+ 1

00720

692B

97

FI

STA

A

MSG33+1

00730

69 2D

CE

6B28

LDX

#MSG4

007 40

6930

DF

FE

STX

TEMP3

00750

6932

96

FF

LDA

A

TEMP3-M

00760

6934

97

F3

STA

A

MSG44+ i

00770

6936

CE

6A8A

LDX

# TABLE

FIND ASCII TABLE OFFSET

00780

.6939

DF

FB

STX

ASCI I + 1

STORE IN OFFSET

00790

69 3B

7F

00FD

CLR

SHI FT

SET SHIFT FOR LETTERS

008)0

* INITIALIZE

ACIA IN

SLOT 3

00830

69 3E

CE

8 00C

LDX

#PRTDAT

008 40

6941

86

03

LDA

A

#$03

008 50

6943

A7

00

STA

A

0,X

008 60

6945

86

4D

LDA

A

#$4D

00870

69 47

A7

00

STA

A

0> X

00890

* SET

OPERAT

ING PARAMETERS

009 )0

69 49

86

97

LDA

A

#$97

00920

69 4B

97

F5

STA

A

MODS PC

SET FOR WIDE SHIFT

00930

69 4 D

DE

EC

LDX

MSG 1 1

00940

69 4F

BD

E07E

JSR

OUT

009 50

69 52

BD

E 1 AC

J SR

IN

009 60

6955

8 1

57

CMP

A

#$57

WIDE OR NARROW SHIFT?

00970

6957

27

04

BEO

S60

WIDE

00980

69 59

86

AC

LDA

A

# SAC

NARROW

009 9 0

69 5B

97

F5

STA

A

MODSPC

SET FOR NARROW SHIFT

01000

69 5D

CE

0BF5

S60

LDX

# S0BF5

SET DELAYS FOR 60 WPM

0)010

69 60

DF

F 6

STX

DELI

01020

69 62

CE

08 64

LDX

#$08 64

01030

69 65

DF

F8

STX

DEL2

01040

69 67

DE

EE

LDX

MSG22

01050

69 69

BD

E07E

JSR

OUT

01060

69 6C

BD

El AC

JSR

IN

INPUT SPEED

01070

69 6F

81

37

CMP

A

#$37

75 WPM?

01030

69 7 1

27

1 0

BEO

S75

YES - BRA

01090

69 7 3

81

31

CMP

A

#$31

100 WPM?

01 100

69 7 5

26

1 6

BNE

SAV

NO - THEN IS 60

01110

69 7 7

CE

0 65D

SI 00

LDX

#$065D

01 120

69 7 A

DF

F 6

STX

DELI

100 WPM

01 1 30

69 7 C

CE

04A2

LDX

# S04A2

01140

69 7 F

DF

F8

STX

DEL2

01150

698 1

20

0A

BRA

SAV

01 1 60

6983

CE

095D

S 7 5

LDX

# $09 5D

01 170

698 6

DF

F 6

STX

DELI

75 WPM

01 180

6988

CE

0 69B

LDX

# S069B

01 190

69 8 B

DF

F8

STX

DEL2

01200

698 D

DE

F0

SAV

LDX

MSG33

01210

698 F

BD

E07E

JSR

OUT

01220

699 2

BD

El AC

JSR

IN

SAVE DATA?

01230

699 5

7F

00F4

CLR

SAVE

01240

6998

81

59

CMP

A

#$59

YES?

01250

699 A

27

03

BEO

YEA

THEN SKIP

01260

699C

7C

00F 4

INC

SAVE

NO - SET FLAG

01270

69 9 F

DE

F2

YEA

LDX

MSG44

01280

69 A 1

BD

E07E

JSR

OUT

OUTPUT C/R AND L/F

01290

•69 A 4

86

3C

LDA

A

# $3C

KILL ECHO ON CONTROL PORT

01300

69A6

B7

8007

STA

A

INPUT+3

01320

♦ START OF

RECEIVE PROGRAM

01340

69A9

0D

CM

SEC

CLEAR ANY FRACTIONAL

01350

69 AA

79

8004

ROL

INPUT

CYCLES OF SIGNAL

01360

69 AD

25

FA

BCS

CH

01370

69 AF

0D

CL

SEC

01380

69B0

79

8004

ROL

INPUT

DISCARD LOW PORTION

I

01390

69B3

24

FA

BCC

CL

OF FIRST CYCLE

0 1 400

69 B 5

8D

3B

START

BSR

DECODE

FETCH CYCLE TIME COUNT

01410

69B7

D 1

F5

TEST

CMP

B

MODSPC

IS IT A SPACE?

01420

69 B 9

23

04

BLS

STBI T

YES - GO MAKE SECOND COUNT

01430

69BB

8D

41

RPT

BSR

HRPT

NO - CHECK AGAIN

0 1 440

69 BD

20

F8

BRA

TEST

01450

69BF

8D

3D

STBI T

BSR

HRPT

MAKE SECOND TIME COUNT

01460

69 C 1

D 1

F5

CMP

B

MODSPC

SPACE?

01470

69C3

22

F6

BHI

RPT

NO - GO BACK AGAIN

0 1 480

69 C 5

C 6

05

LDA

B

#5

YES - LOAD BIT COUNT

01490

69 C 7

37

PSH

B

SAVE BIT COUNT

01500

69C8

4F

CLR

A

CLEAR DATA SPACE

01510

69C9

36

PSH

A

SAVE DATA SPACE

01520

69CA

8D

47

BSR

DELAY 1

DELAY FOR FIRST DATA BIT

01530

69CC

8D

24

NEXT

BSR

DECODE

FETCH CYCLE TIME COUNT

01540

69 C E

D1

F5

CMP

B

MODSPC

SPACE?

01550

69D0

22

0D

BHI

ONE

NO - THEN IS A ZERO

0 1560

69 D2

32

PUL

A

RECOVER DATA

0 1570

69D3

0C

CLC

CLEAR CARRY BIT

01580

69 D 4

46

ROR

A

ROTATE ZERO INTO DATA

01590

69 D 5

33

PUL

B

RECOVER BIT COUNT

01600

69 D 6

5A

DEC

B

FIVE DATA BITS IN?

01610

69D7

27

13

BEQ

ASC

YES - GO TRANSLATE DATA

0 1620

69D9

37

PSH

B

NO - SAVE BIT COUNT

01630

69DA

36

PSH

A

SAVE DATA

0 1 640

69 DB

8D

3C

BSR

DEL AY2

DELAY TO NEXT BIT

01650

69DD

20

ED

BRA

NEXT

GET NEXT BIT

01660

69 DF

32

ONE

PUL

A

RECOVER DATA

01670

69 E0

0D

SEC

SET CARRY BIT TO ONE

01680

69 E 1

46

ROR

A

ROTATE ONE INTO DATA

01 69 0

69 E?

33

PUL

B

RECOVER BIT COUNT

01700

69 E 3

5A

DEC

B

FIVE DATA BITS IN?

017 10

69 E4

27

06

BEQ

ASC

YES - GO TRANSLATE DATA

01720

69 E 6

37

PSH

B

SAVE BIT COUNT

01730

69 E 7

36

PSH

A

SAVE DATA

01740

69 E8

8D

2F

BSR

DELAY2

DELAY TO NEXT BIT

01750

69 EA

20

E0

BRA

NEXT

GET NEXT BIT

01760

69 EC

8D

31

ASC

BSR

OUTDAT

GO OUTPUT DATA

01770

69 EE

8D

29

BSR

DELAY2

DELAY FOR STOP BIT

01780

69 F0

20

C3

BRA

START

RETURN FOR NEXT CHR

01790

69F?

0D

DECODE

SEC

01800

69 F 3

79

8004

ROL

INPUT

CLEAR ANY FRACTIONAL

018 10

69 F 6

25

FA

BCS

DECODE

CYCLES

01820

69F8

0D

ML

SEC

01830

69 F9

79

8004

ROL

INPUT

CLEAR LOWS

0 1840

69FC

24

FA

BCC

HL

0 1850

69 F E

5F

HRPT

CLR

R

CLEAR TIME COUNT

0 18 60

69FF

86

06

LDA

A

#$06

SET CYCLE COUNT

01870

6A01

0D

HH

SEC

01880

6A02

79

8004

ROL

INPUT

FETCH INPUT

0 1890

6A05

5C

INC

B

INC TIME COUNT

01900

6A06

25

F9

BCS

HH

INPUT HIGH? - THEN GO RACK

01910

6A08

0D

HLS

SEC

INPUT LOW

01920

6A09

79

8004

ROL

INPUT

FETCH INPUT

01930

6A0C

SC

INC

B

INC TIME COUNT

01940

6A0D

24

F9

BCC

HLS

INPUT LOW? - THEN GO BACK

019 50

6A0F

4A

DEC

A

DEC CYCLE COUNT

019 60

6A1 0

26

EF

BNE

HH

DONE? -NO- COUNT NFXT CYCLE

01970

6A12

39

RTS

YES - RETURN

01980

6A13

DE

F 6

DELAY 1

LDX

DELI

01990

6A1 5

09

D 1

DEX

DELAY FOR FIRST DATA BIT

02000

6A1 6

26

FD

BNE

D 1

02010

6A18

39

RTS

02020

6A19

DE

F8

DELAY2

LDX

DEL2

02030

6A1B

09

D2

DEX

DELAY BETWEEN PITS

02040

6A1C

26

FD

BNE

D2

02050

6A1 E

39

RTS

02070

♦ DECODE BAUDOT TO ASCII

02090

6A1 F

44

OUTDAT

LSR

A

SHIFT DATA TO FIVE LEAST

02100

6A20

44

LSR

A

SIGNIFICANT BITS

or six-channel receivers are
available for about $60 to $70.
These are crystal controlled so
a crystal for each frequency
used will also be required. Con-
sult the various ham magazines
such as 73 Magazine.

Another choice is one of the
many PSB Hi band VFH scan-
ners around. These are often
excellent receivers, and many
cover at least the important
portion of the two-meter band,
146-148 MHz. Even if their cov-
erage is listed only down to 148
MHz, most will operate at the
lower frequencies. Many hams
use these for monitors.

The last choice is one of the
tunable PSB receivers. Their

0430

INPUT EQU $(NEW ADDRESS)

0811

LDX #INPUT

0812

CLR O.X

0813

LDA A #4

0814

STA A 1.X

Fig-

4. Program additions

for

use with a PiA, other

than the MP-C, for input.

main advantage is you can tune
to find RTTY signals, recogniz-
able by their chirping sound.
Their main disadvantage is lack
of sensitivity and poor selectiv-
ity. This means that in the pop-
ulated areas where there are
many stations, interference is
likely. Also their poor sensitiv-
ity, particularly in the lower-
priced receivers, requires a
stronger signal.

If you already have a good
communications-type short-
wave receiver with an FM detec-
tor, another possibility is to add
a converter. Converter kits are
available for under $40. This
method has the advantage of
requiring no crystals, and you
can tune the entire two-meter
band.

Reliable range of two meters
depends largely on the antenna
height of both transmitter and
receiver. When two stations are
communicating directly to each
other, alternately using the
same frequency (Simplex),
range may vary from a few
miles to 10 or 20 miles, al-

though much longer ranges are
obtained. A repeater is a device
that receives a signal and re-
transmits it on a different fre-
quency, usually with higher
power and from a better anten-
na location. Through repeaters,
ranges of maybe 30 to over 100
miles are usual. Many localities
now have RTTY repeaters oper-
ating.

How do you find the fre-
quency^) used for RTTY? The
best way is to ask a ham. Our
local computer club has a dozen
or more ham members, so try
your club. If you don’t know any
hams, maybe a friend does.
With a tunable receiver, you
can listen. If all you hear is
voice, keep listening, particu-
larly in the early evening. Even
RTTY repeaters are used more
for voice than RTTY. If yours is
a crystal-controlled set, then
you must find the frequency in
order to obtain the proper crys-
tals.

Some Possibilities

Amateurs are not permitted

to broadcast one-way signals,
so a ham buddy cannot legally
send to you, a non-ham. But
suppose a couple or more hams
in the computer club arrange a
schedule to transmit programs
back and forth to each other at
8 pm Tuesday. There is no
reason you shouldn’t eaves-
drop, and if you cannot hear
one of them, possibly the other
is on your side of town.

Programs can be stored on
tape instead of being printed.
They can then be loaded into
the computer or printed from
the tapes. It makes no differ-
ence what your tape baud rate
is; it will simply takemuch more
tape than usual because of the
low speed of incoming data.

If anyone would like to try
this program but doesn’t want
to key it in by hand, I can fur-
nish an object tape for $4.
Please specify starting address
of 0100, 2000 or 6900. Alternate-
ly, I could provide a tape copy
of the assembler program for
the SWTP Co-Res Assembler.
All tapes are 300 baud KC.M

108 Microcomputing January 1980

For Apple II

SCORE*00000 HI-SCORE *00000

VROE

4 M? MYSTERY
A-30 POINTS
*■20 POINTS
*-10 POINTS

HIT ANY KEY TO ESCAPE

' SCORE

= 00600

HI-SCORE*0000O ^

RPPLE

*

*

* * #

INVADER

m **

* m **

€>

>

A

, vt

V*

3

*

*** A

The Game That Drove Japan CRAZY!

SUPER INVADER

(COKCMttl* MI-SCO«f»39l0

* a * * *

• **•*•* m *

/ r A /•

* • • «

• Features superb high resolution graphics, nail-biting tension and
hilarious antics by the moon creatures!

• Self-running “attract mode” of operation for easy learning and
demonstrating of the game.

• As good in every way as the famous Invaders arcade game.

• High speed action !

• On cassette or 5” floppy disc.

CS-4006 CS-4503A

Only $19.95

Requires 24K Apple II with Integer Basic
(main program is in machine code).

• Sound effects!

me

Order Today

Send payment plus $1.00 shipping and handling in the U.S. ($2.00 foreign) to
Creative Computing Software, P.O. Box 789-M, Morristown, N.J. 07960. N.J. residents
add $1 .00 sales tax. Visa, Master Charge and American Express orders may be called in toll
free to 800-631-8112 (in N.J. 201-540-0445).

»^C169

Produced under exclusive
license from Cosmos Software,
Astar International Co., Ltd.

sensational

software

creative

computing

software

Creative Computing
Software

P.O. Box 789-M
Morristown, NJ 07960

Dealer inquiries invited.

Reader Service— see page 227

Microcomputing January 1980 109

Leslie R. Schmeltz
3224 Magnolia Ct.
Bettendorf IA 52722

“Core” and More
for Your Apple

You’ve yawned through the games. For serious computing, you’ll need accessories.

A personal computer is much [“
like a Barbie doll— once
you have purchased the bare
unit, the price of wardrobe and
accessories can easily equal or
surpass the original price tag!
Small wonder the new micro-
computer owner feels in-
timidated by the vast array of
hardware and accessories avail-
able for his system.

Like you, I studied specifi-
cation sheets for quite a while
before purchasing my Apple II.

The standard features included
are impressive, but by no
means complete. My applica-
tions are different than yours,
so our systems must be con-
figured differently. The stan-
dard 16K Apple II can do a lot of
processing, but you must have
a TV monitor (or modulator) to
see what it’s doing and a
cassette unit to store what it
has done. Perhaps your dealer
included the cassette recorder
and modulator in the price; if
not, you have already started
the process of accessory pur-
chasing.

Once you have played the
standard game a few times and
(I hope) studied the excellent
documentation supplied by Ap-
ple, you will probably be itching
to begin your own applica-
tions. If you purchased your Ap-
ple II with full 48 K RAM, disk
drive(s), I/O cards, modem,

110 Microcomputing January 1980

Survey results.

ATV Research (402)987-3371 24 hours

13th & Broadway NO CC/M.O.-none/Cat-Free

Dakota City NE 68731

• “Pixie-Plexer” (PXP-4500) for advanced designers, experimenters and
builders desiring to work with color and/or audio as well as b/w video signals.
$24.50

• “Pixie-Verter” (PXV-2A) rf modulated oscillator $8.50

• Video monitors.

Advanced Computer Products (714)558-8813 8-7 PST

1310 “B” E. Edinger All CC/M.O.-$10.00/Cat-Free

Santa Ana CA 92705 Items guaranteed.

• 16K memory expansion kits with instructions and jumpers: NEC
UPD416-1 (200 ns)— $89.95, Toshiba 4116-4 (250 ns)— $89.95, Hitachi
4716-4 (200 ns)— $89.95, Mostek MK4116-2 (200 ns)— $89.95

California Digital (213)679-9002 8:30-5 PST

4738 156th Street MC, VISA/M.O.-none/Cat-Free

Lawndale CA 90250 90-day guarantee

• NEC UPD416D 16K memory chip set 8/$65

• Digicast AV/100 rf modulator $29.95

Candex Pacific, Inc. (415)364-8427 9-6 PST

693 Veterans Blvd. No CC/M.O.-none/Cat-none

Redwood City CA 94063 (data free) 30-day guarantee

• Tape activator controls audio tape recorder from the game I/O connec-
tor. Can control other devices not exceeding Vi Amp current. Has connec-
tor for game controls or another activator. Each model addressed by a dif-
ferent POKE command, if multiple units are used each must be a different
model. Model numbers: 100-00; 100-01; 100-02; 100-03. $39.95

Circuit Specialists (800)528-1417

1344 North Scottsdale Rd. (Box 3047) MC, VISA/M.O.-$15 phone, mail-

Tempe AZ 85281 none/Cat-Free

• Pkg. of eight 4116 16K memory chips $159.95

• EPROMs, ICs, components.

Deltroniks (404)458-4690

5151 Buford Hwy. MC, VISA/M.O.-none/Cat-Free

Atlanta CA 30340 Memory chips 100 percent

guaranteed.

• 16K memory expansion package $80., 32K $160.

• ICs, components.

V

The Heuristics SpeechLab is one of the many accessory items of-
fered for the Apple II. (Photo courtesy of Heuristics, Inc.)

printer, etc., this article may be
only of passing interest to you.
I suspect (from personal ex-
perience and an informal sur-
vey of owners in our local Apple
users group) that most com-
puter hobbyists start out with a
“plain Jane” system and the in-
tention of adding hardware and
accessories as interests
develop and finances permit.
Many of us in the latter group
(you know— the ones unable or
unwilling to commit several
kilobucks to our initial pur-
chase) have now reached the
point of looking for ways to ex-
pand the capabilities of our
systems.

Many applications require
additional hardware (and soft-
ware) of a specialized nature.
Amateur radio, for instance,
could use audio-to-digital con-
verters, antenna rotor controls,

ASCII-to-five-level conversion,
logging systems, repeater con-
trol and ac controllers, to men-
tion only a few of the countless
possibilities. Someone in the
diverse group of Apple owners
and accessory designers has
probably worked up items that
will be of direct use in your ap-
plication, but where do you find
out about them?

Sources of Information

Computer manufacturers
publish a great deal of informa-
tion about their products. Ap-
ple literature describes not only
the basic system, but also nu-
merous accessories available
from dealers. You probably
studied some of this literature
in reaching your decision to
purchase the Apple II and are
already aware of most items of-
fered by Apple. Unless your

literature is quite recent, you
may have missed some, since
new items are continually be-
ing added to the Apple line.

Your local computer em-
porium can be a great source of
information. Most manufac-
turers maintain a mailing list of
dealers and send literature on
new products as they become
available. I’m sure your dealer
would be happy to watch for
product announcements of
specific interest to you.

If you are fortunate enough
to live in an area that has an Ap-
ple users group, much valuable
information is available.
Chances are some of the other
members have interests similar
to yours and will be willing to
work together on applications.
A file of literature received by
various members of the group
would be a good source for in-
formation on hardware and ac-
cessory items.

Magazines, newsletters and
direct-mail advertising are all
directed toward disseminating
information about available
new products. Manufacturers
spend a great deal of money at-
tempting to inform you of the
items they have to offer, but ob-
viously cannot advertise each
product in every issue of every
publication. Many magazines
offer reader service cards,
which enable you to obtain
literature on specific products.
If you don’t see the particular
company listed that interests
you, a letter request will usually
bring a catalog by return mail.
Some companies request an
SASE or small fee for their
literature; this is usually noted
in their advertisements.

Digital Dynamics, Inc.
310 C. Breesport
San Antonio TX 78216

(512)341-8782 9-5
MC, VISA/M. O.-none/Cat-Spec.
sheets free. Defective items
repaired or replaced.

• Computer canopy dust cover. Standard color walnut, other colors
available. $12.95

Digital Research Corporation (of Texas) (214)271-2461 8:30-5

PO Box 401247K MC, VISA, AE/M.O.-$10/Cat-Free

Garland TX 75040 90-day money-back guarantee

• 16K dynamic RAM chips (250 ns) 8/S89.95

• EPROMs, ICs, components, etc.

Electronic Systems (408)226-4064 24 hours

PO Box 21638 MC, VISA/M.O.-none/Cat-Free

San Jose CA 95151 Lifetime guarantee

• National 4116 16K RAM chips (250 ns) $8

• 2102 IK RAM chips (450 ns) $1.75

• Apple II serial I/O interface— adjustable 0-30,000 baud, plugs into any
peripheral connector. Includes operating software. Board only (#2) $15,
with parts (#2A) $42, assembled and tested (#2C) $62

• Many other boards and kits.

Elektrik Keyboard, Ltd. (312)751-1555 10-8 M-TH, 10-6 F, S

1920 N. Lincoln Ave. No CC/M.O.-check/Cat-available

Chicago IL 60614 soon

• Joy Stick— Applestix. Uses everything the game I/O can control. Has
four paddles, three switches, four LEDs. $180.

• Multiplexing card. Expands socket into five sockets for attaching extra
paddles, joystick, light pen.

• Travel case. Heavy duty, foam lined, metal reinforced flight case. Car-
ries computer and two disk drives. $199.

Godbout Electronics (415)562-0636 24 hours

Box 2355 MC, VISA/M. 0.-$15/Cat-Free

Oakland Airport CA 94614 1 year against defects in

materials or workmanship

• Godbout 16K conversion (250 ns) $109

• EPROMs, ICs, components, etc.

D.C. Hayes & Associates, Inc. Sold only through Apple dealers.

PO Box 9884
Atlanta GA 30319

• Micromodem II provides capabilities of communications card and
acoustic coupler, plus programmable automatic dialing and answering.
Plugs into Apple expansion slot, direct coupled to phone line. Under $400.

Microcomputing January 1980 111

Henwood Enterprises, Inc.
1833 E. Crabtree Dr.
Arlington Heights IL 60004

Ithaca Intersystems
PO Box 91
Ithaca NY 14850

• Hitachi 16K memory expansion set
retail dealers).

Jameco Electronics
1021 Howard Ave.

San Carlos CA 94070

(800)323-7360 9-5 CST
MC, VISA, AE/M.O.-none/Cat-none
1 year against material or labor
defects.

(607)257-0190 9-5 EST
MC, VISA (4 percent surcharge)
M.O.-none/Cat-Free 100 percent
lifetime guarantee for chips.
$140 (also available through many

(415)592-8097 8-5 PST
No CC/M.O.-$10/Cat-41<p stamp
90-day warranty

(415)592-1800 8:30-5 PST
MC, VISA/M. O.-$10 (CODs and
CC)/Cat-Write Items guaranteed

Survey

This survey was undertaken
with a primary motive in
mind— I was interested in some
accessory items for my Apple II
and wanted to see what was
available and from whom. It oc-
curred to me that other Apple
owners might be in the same
situation, thus this article.

I have attempted to provide a
reasonably compact and com-
plete list of hardware and ac-
cessory items most likely to be
added by the hobbyist with a
relatively bare Apple II. I made
no attempt to locate all items
compatible with RS-232, cur-
rent loops, parallel and serial
ports, etc.— the list could be
endless! I included only those
items advertised as being de-
signed specifically for the Ap-
ple II. Since information on pro-
ducts manufactured by Apple
Computers, Inc., should be
readily available to all owners, I
did not include these in this
listing.

It should be emphasized this
article is in no way intended to
duplicate the advertising ef-
forts of any supplier; it merely
provides a compact listing of
items and sources from which
you can obtain specific infor-
mation regarding them. I have
attempted to answer for you
the same kinds of questions we
all have when dealing with any
supplier.

Survey Procedure

A questionnaire was sent to
as many sources as I could lo-
cate from magazine ads, direct-
mail fliers and catalogs. As
mentioned earlier, I included
only those suppliers indicating
hardware or accessories for the
Apple II.

Forty-five questionnaires
were mailed, and 27 were re-
turned within four weeks . . .
a response rate of 60 percent.
Much supplementary informa-
tion in the form of literature
sheets, catalogs and product
information was received and
used to provide the information
contained in the listings.

Certainly there are suppliers
not mentioned in this article for
various reasons— question-
naires not returned, names and

• UPD416 (MK41 16) 16K RAM chips $14.95

• EPROMs, ICs, components

Microproducts (213)374-1673 8-5 PST M-F

2107 Artesia Blvd. No CC/M.O.-none/Cat-Free

Redondo Beach CA 90278 Guarantee offered

• Centronics 779/SWTP PR40 printer interface (MP7101-2) $49.95

• General-purpose 8 bit parallel output port card (MP7101-3) $44.95

• EPROM programmer for 5 volt 2K EPROMs (MP8102-1) $99.95

• EPROM socket adapter adapts 5 volt EPROMs to Apple ROM sockets.
(MP8105-1) $14.95

• Apple II to Superkim downloading card with cable and connector
(MP9102-2) $74.95

Mikos

419 Portofino Drive
San Carlos CA 94070

• Hitachi 2114(250 ns) $7.99

• National 2114 (450 ns) $7.25

• 2102 AN-ZL (250 ns) $1.60

• 2102 AN-4L (450 ns) $1.25

• Full line of SSM, Wameco and CCS boards and kits.

Dan Paymar No Phone Orders

PO Box A-133 C.S. 6800 ?/?/?

Costa Mesa CA 92627 90-day replacement guarantee

• Lowercase adapter— hardware modification that allows a program to
display lowercase characters on the monitor, also adds some symbols to
make complete 96 character ASCII set. (Peripherals Unlimited text editor/
word processor can be ordered or converted for use with the LCA) $49.95

• Wrapple dust cover for Apple II $8.95

• Wrapple II dust cover for Apple II plus 1 or 2 Disk Ms on top $9.95

Heuristics, Inc. (415)948-2542 8-5 PST

900 San Antonio Rd. CC accepted/M.O.-none/Cat-none

Los Altos CA 94022 1 year guarantee

• Model 20A 32 word SpeechLab for Apple includes ROM-based software,
extensive manual. Applications include voice control games, data entry,
research, etc., $189

• Microphone (noise cancelling) NC-2 $85

Integrated Circuits Unlimited (800)854-2211 (Cal. 800-542-6239)

7889 Clairemont Mesa Blvd. 24 hours MC, VISA, AE/M.O.-none

San Diego CA 92111 Cat-Free “Unlimited guarantee”

• 4116 16K RAM chips $11.50

• ICs, components, video monitors, etc.

Interactive Structures, Inc. (215)382-8296 9-5 EST

Suite 204, Science Center ?CC/M.O.-none/Cat-Free

3401 Market Street 1 year guarantee

Philadelphia PA 19104

• AI-02 analog data acquisition system. Approx. $210

• AO-03 digital to analog board. Available soon, price TBA

• VIP-4 video interface. Available soon, price TBA

• EC-07 editing console. Available soon, price TBA

• SI-01 serial interface. Available soon, price TBA

International Electronics Equipment Corp. (305)595-2386

PO Box 522542 MC, VISA/M.O.-none/Cat-none

Miami FL 33152 Guaranteed working

• Apple interface for Okidata CP1 10 printer (must be used in conjunction
with Apple’s interface board). $100

• Okidata CP1 10 $650

112 Microcomputing January 1980

When the people
behind the products count!

As the CPU Shop, we have been dedicated to meet-
ing the needs of the microcomputer user. The suc-
cess of the CPCJ Shop has led to ComputerCity—
the merging of our manufacturing, wholesale and
mail order divisions with our rapidly expanding re-
tail outlets to provide the increased products and
services the microcomputer consumers of today
and tomorrow want— and need. We remain dedi-
cated to providing the same service, technical assis-
tance and fair pricing you’ve come to expect from

the CPG Shop.

David C. Lourie, President

■f-v- ,>\.r

ComputerCity Sampler
Disk Drives

When you’re ready to add disk storage to your TRS-80*, we’re here to help.
Our CCI-100™ and -200™ drives offer more capacity than Radio Shack 35-Track (85K Bytes) drives. These drives
are fully assembled, tested and ready to plug-in the moment you receive them. They can be intermixed with each
other and Radio Shack drives on the same cable. 90 day warranty.

CCI-100™ 40 Track (102K Bytes) $399.00 CCI-200™ 77 Track (197 K Bytes) $675.00

Printers

Letter Quality High Speed Printer

NEC Spinwriter: In-
cludes TRS-80* inter-
face software, quick
change print fonts, 55
CPS, bidirectional,
high resolution plot-
ting, graphing, pro-
portional spacing and

tractor feed assembly. 90 day warranty $2979.00
Also: Centronics, Paper Tiger, HI Plot Digital Plotter
16K Memory Up-grade Kits
Fast and ultrareliable $99.00

DISK OPERATING SYSTEMS
NEWDOS by Apparat+ $49.95

NEWDOS “PLUS” by Apparat + $99.95

DOS 3.0 by the original author of 2.1 $49.95

DISKETTE TRS-80*

BUSINESS SOFTWARE BY SBSG

Free enhancements and upgrades to registered
owners for the cost of media and mailing. 30 day free
telephone support User reference on request.

Fully Interactive Accounting Package: General Ledger,
Accounts Payable, Accounts Receivable and Payroll.
Report generating.

Complete Package (requires 3 or 4 drives) $475.00
Individual Modules (requires 2 or 3 drives) $125.00
Inventory II: (requires 2 or 3 drives) $ 99.00

Mailing List Name & Address II
(requires 2 drives) $ 1 29.00

Intelligent Terminal System ST-80 III: $ 1 50.00

The Electric Pencil from Michael Shrayer $ 1 50.00
File Management System: $ 49.00

Budget Control Program 11 by CSA $ 49.95

Cash Register System II by CSA $ 99.00

— z:

ComputerCity

A division of CPU Industries, Inc. ^cios
V75 Main Street, Dept. K-l Charlestown, MA 02129^ |

Hours: 10AM - 6PM (EST) Monday - Saturday
For detailed information, call 617/242-3350
Massachusetts residents add 5% Sales Tax

CCI-100 and -200 are ComputerCity Inc. trademarks
* Tandy Corporation Trademark + Requires Radio Shack TRSDOS*

TO ORDER CALL TOLL FREE 1-800-343-6522

Massachusetts residents call 617/242-3350

Retail Store Locations:

175 Main Street, Charlestown, MA
K Mart Plaza, Manchester, NH
50 Worcester Road(Rt.9), Framingham, MA
165 Angell Street, Providence, RI

Visa and Master Charge accepted

Franchise and dealer inquiries invited

y* Reader Sen/ice— see page 227

Microcomputing January 1980 113

Peripherals Unlimited (213)595-6858 9-5 PST

2633 E. 28th St. Suite 622 ? CC/M.O.-none/Cat-SASE

Signal Hill CA 90806 90 days labor, 1 year parts.

• Universal parallel card— intelligent I/O control, configuration of I/O can
be changed to meet particular needs via user programmable driver with
battery back-up. Software inc. $179.95

• Also carries the lowercase adapter.

Powersoft, Inc. (Products sold to dealers only)

PO Box 157 Catalog on request

Pitman NJ 08071

• Light pen (ZXX 0003)— plugs directly into game I/O connector. Supplied
with demonstration software. $34.95

Priority 1 Electronics
16723 Roscoe Blvd.
Sepulveda CA 91343

(800)423-5633 (Cal. 213-894-8171)
8-6 PST MC, VISA/M. O.-$10/Cat-
Free with order. Chips meet or
exceed manufacturers specs
• 16K memory expansion kit (200-250 ns) $69

(617)242-3350 9-7 M-F, 9-6 Sat. EST
MC, VISA/M. O.-none/Cat-Free
90-day guarantee

The CPU Shop
39 Pleasant Street
Charlestown MA 02129

• NEC UPD416D 16K (300 ns) 8/$85

• NEC UPD416-1 16K (250 ns) 8/$87

• NEC UPD416D-2 16K (200 ns) 8/$89

• Dealer for complete Apple line and related software.

Tri-Tek (602)995-9352 9-5:30 M-F

7808 N. 27th Avenue MC, VISA/M.O.-$10/Cat-Free

Phoenix AZ 85021

• NEC UPD416 16K (300 ns) $18, 8/$128

• NEC UPD416-2 16K (200 ns) $20, 8/$144

• 1C, components.

addresses not located in the ini-
tial search, products recently
developed and marketed. If you
know of (or are) a supplier not
listed, please send me as much
information as you can so the
listings can be expanded and
updated at a later time.

Listing Format

The listings that follow are
set up alphabetically and con-
tain the following information:

Name Number and hours for

phone orders

Address Credit Cards Accepted/

Minimum Order/Catalog
City, State, Zip Guarantee (if offered)
Terms

• Items offered (brief description and price).

Information in the listings has
been taken from questionnaire
responses and/or condensed
from catalog descriptions pro-
vided by each supplier. Ac-
curacy of the information is not
guaranteed , and you should in-
vestigate further prior to actual
purchase of any item described.
None in any category indicates
no information received regard-
ing that item.

Summary

I have made no attempt to
judge the quality of either prod-
ucts or vendors in this article.
When considering the pur-
chase of any additional items
for your Apple II, you should:

1. Carefully read the descrip-
tion so you know exactly what
you’re buying.

2. Check with your local

dealer. Perhaps he has, or
would be willing to get, a unit
you could see prior to making
your decision.

3. Ask around. Other hob-
byists in the area may have
dealt with the supplier involved
and be able to tell you some-
thing about the quality of prod-
ucts available.

4. Look through your back
issues of this and other

magazines. Someone may have
reviewed the particular item at
a time when you weren’t in the
market and didn’t pay much at-
tention. (If you don’t find a
review and decide to purchase
the item, how about writing
one? It’s easier than you think
and could help defray the cost!)

5. Don’t hesitate to request
more detailed information from
either your dealer or the manu-

facturer. Manuals are often
available separately for a
nominal cost and provide more
detailed information than a
spec sheet or catalog descrip-
tion can provide.

6. Carefully read the guaran-
tee (if one is offered) and ques-
tion any provisions you don’t
understand.

7. Caveat emptor! (Let the
buyer beware!)*

every four years. . .

. . .the world’s best athletes gather to com-
pete for the coveted gold medal. This year
you can more easily follow this competition
with Med System’s Athletic Index.

This package will allow you to search
events based on country, sport, score, time,
year, or the name of an athlete, or any com-
bination of these. Year searches can be given
any range. All the old records, plus trivia and
brief descriptions, are at your fingertips.

The Athletic Index is now being sent
with the complete statistics for all the winter
competitions through the XXI Olympiad in
1976 at no extra charge. The summer statis-
tics will be available early in 1980.

TRS-80 LI I 16K cassette $9.95
N.C. residents please add 4% tax.

Med Systems Software

P.O. Box 2674, Chapel Hill, N.C. 27514
*^M119

0

1

BEST

BUY ON

COMPUTERS

&

DISKETTES

10 — $37.50 + $1.00 Shipping

50 — $172.50 + $1.50 Shipping
100 — $299.50 + $2.00 Shipping
8” BASF or Georgia Magnetics
5V4” Verbatim

OSI Challenger III 56K, 2-8" Drives,
Fortran, Cobal & 3 - Basics . . . $3995.00

Cromemco SYS - 3 ONLY $4895.00

RS232 — DB25 Connectors
FE 2.95 MALE 1.95 HOOD .95
Call For Discounts on Additional Items

■ Deale

feus

Dealer Inquiries Invited

R#1 Box 193 U.s. 31
Berrien Springs, Ml 49103
(616) 429-3034

is* A112

DISK OPERATING SYSTEM

KMMM

INSIST ON THE ORIGINAL
(BECAME OPERATIONAL MID 78)
VERSIONS AVAILABLE FOR:

PET KIM TIM
SYM AIM

INCLUDES DISK FILE PATCHES
FOR MICROSOFT BASIC
CALL OR WRITE FOR PRICES
AND NAMES

OF SATISFIED CUSTOMERS
^W36

WILSERV INDUSTRIES
P.O. BOX Ilf

HADDONFIELD, N. J. 08033
( 800 ) 287-8898

114 Microcomputing January 1980

YOURS

FREE!!

A GIANT BOOK OF 80 PROGRAMS FOR
THE TRS-80* AS A FREE GIFT WITH
YOUR CHARTER SUBSCRIPTION TO
80 MICROCOMPUTING . AN ALL NEW
MICROCOMPUTER MAGAZINE FOR
THE TRS-80 OWNER AND USER

That's right. You can receive a giant book of programs for your TRS-80 and have the distinc-
tion of being a charter subscriber to the largest magazine published on the TRS-80.

PROGRAMS

80 MICROCOMPUTING contains a wealth of information on business, personal and educa-
tional software. New product reviews are featured each month, along with new applications
for everything from text editing to music.

Subscribe today and take advantage of this super charter subscription offer ... 12 months
of 80 MICROCOMPUTING for $12 ... (that's half the newsstand price)! Plus, if you
subscribe now, we will send you FREE OF CHARGE a giant book of 80 PROGRAMS for your

TRS-80. *(TRS-80 is a trademark of the Tandy Corporation.)

YES! SIGN ME IIP AS A
CHARTER SUBSCRIBER TO
80 MICROCOMPUTING FOR
JUST $1.00 PER COPY. AND
SEND MY FREE COPY OF 80
PROGRAMS WHEN YOU
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□ 12 issues — $12 (save $12) □ 36 issues — $36 (save $36)

□ Payment enclosed □ Please bill me

Bill my □ Visa □ Master Charge □ American Express

Card #

Name Signature

Street

Mail to:

80 MICROCOMPUTING
POB 981

Farmingdale NY 11737
Exp. date_

City _

.State.

.Zip.

301 K33

Canada: $12 per year US funds. Add $2 per year for Canadian dollars. All other foreign subscriptions: $20 one year only, payable in US currency.

The Metamorphosis of
a “Custom” PET

This all-in-one design offers maximum portability in a disk-based PET.

Robert Freeman
Penn Park J-382
Morrisville PA 19067

A lmost everyone is familiar
with the PET computer
from Commodore; it is one of
the most popular “appliance-
type” computers and features a
built-in video display and cas-
sette recorder. The PET uses the
6502 microprocessor and Micro-
soft BASIC— the fastest combi-
nation around.

But like many computer own-
ers, I soon became impatient
with the slow cassette recorder.
Also, like many other computer

owners, I wanted to expand my
system to include more memo-
ry, more I/O, etc. But I still
wanted a single compact unit
such as the original PET. That
started me thinking about a
“custom” PET, with a built-in
floppy disk system and extra
memory.

Considerations

1. I wanted to maintain the
portability of my PET.

2. I wanted the disk on the
front for easy access.

3. I would only use the cas-
sette recorder occasionally
once I had the disk installed.

4. I wouldn’t need the PET
keyboard, as I had already built

an external keyboard.

5. I needed room to mount a
floppy disk drive (or drives), flop-
py disk controller, memory ex-
pansion, power supply for the
disk drive and control boards. I
needed more physical space for
expansion.

I then had to consider other
limitations: lack of hard cash. I
could supply the effort and the
metal bending, but where could I
get an economical disk control-
ler and software to run my disk?
And how could I increase memo-
ry capacity for a reasonable
cost?

After looking around a while, I
found there wasn’t much
choice. The only company that

sold a separate disk controller
board for the PET was CGRS
Microtech, Inc., of Southampton
PA. This turned out to be an ex-
cellent choice since the CGRS
Microtech board (EXS100) is ac-
tually two boards in one: a disk
controller and PET-to-S-100
adapter (see Fig. 1).

The board is the size of the
standard S-100 card, with the
disk controller (and ROM space)
using the upper half of the board
and the S-100 adapter for memo-
ry expansion on the lower half of
the board. The cost of this card
assembled and tested was $299
for the disk controller and cas-
sette software. Their ROM ver-
sion of software (by Wilserv In-
dustries, PO Box 115, Haddon-
field NJ 08033), which I pur-
chased, was an additional $60
(see Photo 1).

With the CGRS Microtech
S-100 memory expansion adap-
ter, I was able to buy inexpen-
sive memory as needed, add all
kinds of extra I/O and many so-
phisticated types of S-100 cards
and have hardware and soft-
ware to support three disk
drives.

With most of the pertinent
facts in mind, I was now ready to
start my planning and design.

Decisions, Decisions

My initial design decisions in-
cluded using the CGRS control-
ler, beginning with one disk
drive, using a 5 slot (S-100)
motherboard, adding 16K extra

Photo 1. The CGRS Microtech disk controller board showing the PET-to-S-100 adapter and disk con-
troller section.

116 Microcomputing January 1980

Fig. 1. Power supply for both disk and S-100. (Parts purchased from
AB Computers, 115 East Stump Rd., Montgomeryville PA 18936.)

memory, using an external
keyboard and eliminating the
tape cassette from the front and
plugging it in back when I need-
ed it.

The next big decision I made
was to eliminate the sloped
front and make a new top cover
for the PET, but leave the rest of
the sheet metal as it was. Now,
this may seem to you like a
rather strange way to treat a
PET, but I wanted to have the ex-
tra room.

Before making the final deci-
sion to start construction, I went
to CGRS Microtech to see their
complete disk system in opera-
tion. I was surprised to learn
their controller card would also,
with a few jumper changes,
operate eight inch disks (see
Photo 2) as well as the mini-
disks. The system they let me
use consisted of their standard
disk package with two eight
inch disks. I was pleased to find
it simple to use and foolproof in
its operation.

New Cover

I made the case out of a piece
of 1/16 inch thick aluminum (27
inches wide x 29 inches long)
that I cut out and bent in four
places so it would fit directly on-
to the original PET hinge and
open the same way as the origi-
nal PET case opens.

Then, instead of leaving a
large hole in the top between the
PET and the CRT, I made a small
hole to run wires down from the

CRT and a hole for a fan to draw
the air through the CRT into the
bottom of the case. Proper venti-
lation is important in the original
PET. A fan is almost necessary
there.

I moved the power transform-
er from the base to the back wall
(back of PET, lower half). Then, I
replaced the part of the PET that
held the tape deck and keyboard
with my square box. That made
my PET about one inch taller. In-
stead of sloping down at front
for the keyboard, it comes
straight across and is the same
size as the original PET box.

Between the main logic board
and the left-hand side of the
PET, there was room for a five
slot S-100 motherboard (where
the cassette used to be) as well
as the disk controller card,
memory cards and several other
S-100 cards. The fan is mounted
horizontally between the CRT
housing and the new case to
provide ventilation to all the
electronics.

I already had replaced the
original keyboard with a full-size
keyboard, so there was no need
for the PET keyboard. This left
room to put three drives in the
new enclosure. Right now I only
have one disk drive, which is
mounted horizontally so it looks
better. I will mount future drives
vertically, so I will have space
for a total of three while still
keeping the PET in one com-
pact, portable, easy-to-move-
around package.

Power Supply

The power supply drives the
disk and the S-100 board. It re-
quires + 8 volts at 5 Amps, ±16
volts at 3 Amps for the S-100
bus, +5 volts at 2 Amps and
+ 12 volts at 2 Amps for the disk.
I assembled the power supply
with parts that were on hand or
readily available for less than
$30. A complete power supply
kit is available from CGRS for
$55. The power supply is
mounted in the upper corner of
the new box behind the Shugart
drive.

Assembly

The assembly went together

well. The cables for the S-100 ex-
pansion system (Photo 3) con-
nect to the PET memory expan-
sion port and run underneath
the PET main logic board, up
alongside of the S-100 mother-
board, and plug into the CGRS
EXS100. Another cable con-
nects the EXS100 to the Shugart
disk drive. Two more cables con-
nect the S-100 motherboard and
the Shugart drive to the power
supply.

You may notice the small cir-
cuit board in the right-hand rear
corner of the PET. It has nothing
to do with the disk; it is a small
amplifier for sound. When soft-
ware has sound built in, I don’t

Photo 3. Internal assembly of Bob’s PET.

Microcomputing January 1980 117

FOR THE VERY BEST IN
NORTH STAR COMPATIBLE SOFTWARE:

TEXT- PROCESSING: ‘TFS’ text processing system. The most powerful word
processor/output formatter available for North Star! Justifies both left and
right margins. Paging, page numbering, block moves, file merges, global
search and change. You can save and load text files to or from disk. Plus
much, much more! ‘TFS’ has everything you want in a text formatter. Minimal
system: 24K RAM starting at 0000H. Includes extensive user’s
manual. -$75.00

ASSEMBLER AND OPERATING SYSTEM: ‘Arian’ is the assembler/operating
system you need for both the large and small jobs. Supports all wanted
features, plus those special extras: user defined commands, disk based com-
mands, transient program area, memory management, and dynamic file crea-
tion/deletion. Also: You can save and load obj./source files to and from disk.
Minimal system: 24K RAM starting at 0000H. Extensive user’s manual in-
cluded.- $50. OO.Special utility package for ‘Arian’. -$50.00
‘TINY’ PASCAL!!: The famous Chung/Yuen ‘Tiny’ Pascal. A great way to write
structured programs that execute up to 25 times faster than Basic. Includes
source to the compiler, written in Pascal! (You can even re-compile the com-
piler.) Supports recursive procedures and functions as well as if . . . then
. . . else . . . then, case, while, repeat/until, etc. (You need 24K RAM; 36 to com-
pile the compiler). -$40.00

INSURANCE AGENTS: We have a great package just for you! The ‘CRS’ client
record system. A complete program system created to supply your agency
with all necessary and pertinent information about your clients and pros-
pects. This package is specifically designed with use as a marketing tool in
mind! Lets you search your records any way you want and has a powerful
sieve’ search to find correlations and exceptions (i.e., All the clients that have
homeowners with you and not auto, etc.). Much, much more. Minimal system:
40K RAM starting at 2000H, two disk drives. Holds up to 1400 names double
density, 700 single density. Comes with extensive user's manual -$250.00
Plus much more. Write for catalog or call 217-344-7596
Also, custom programming, consulting and on-sight installation is available
through Supersoft. Call or write us.

Specify single or double density.

P.O. Box 1628. Champaign, IL 61820

"IT PAYS FOR ITSELF . .

Announcing Our
Integrated Accounting System

General Ledger

Accounts Receivable II Payroll II Accounts Payable

* Totally modular . . . buy only what
you need

* Fast, efficient and easy to use

* Cursor control for SOL, SOROC,

ADM-3, ADDS- 100, Hazeltine
1500, Intertube

* 65 Programs for maximum
flexibility

* Too many features to list here!

Prices: General Ledger Plus:

One package: $225.00 Two packages: $300.00 All four: $350.00

Manual (for all 4 packages): $20.00, credited towards pur-
chase. Programs use North Star Basic, 2 disk drives (double
or single density), 32 K of memory. Specify video device
when ordering.

[master charge]

THE INTERBANK CARO

ECOSOFT

P.O. Box 68602
Indianapolis, IN 46268

Phone orders:

(317) 253-6828

Photo 4. Completed “ custom " PET.

have to carry a separate ampli-
fier and speaker with me be-
cause it’s also built right into my
PET.

Ease of Operation

The software from Wilserv In-
dustries is great! You may
operate it two ways: from BASIC
or from its own monitor. From
BASIC you can:

a. Save a program

b. Load a program

c. Run a program

d. Write a sequential data file

e. Read a sequential data file

f. List the disk directory

g. Update a program

h. Delete a program

i. Initialize a new diskette

j. Compress a diskette (physi-
cally recover space from a de-
leted program)

From the disk monitor, which
is invisible to the BASIC user,
you can:

a. Perform all of the above BA-
SIC commands

b. Save assembly-language
programs

c. Load assembly-language
programs

d. Alter the file load point

e. Move blocks of memory

f. Echo the console character

g. Go to any location in memory

h. Move programs from disk to
disk

Move Utility

Move is used to make backup
diskettes or to copy programs
from disk to disk. The interest-

ing point is that it will work with
a single disk drive or a multiple
disk-drive system. Its operation
follows along logically, so it will
not let you make any errors in
copying.

The disk directory may be
listed in short form (program
names only) or long form. The
long form lists the program
name, number of sectors used,
date the program was put on the
disk, the number of program up-
dates along with the date of the
latest update, whether the pro-
gram is BASIC or assembler and
the starting location of the pro-
gram in memory.

The disk software is IBM3740
standard and allows any IBM
standard diskette (such as
Radio Shack) to be read.

Conclusion

I now have a fantastic PET
system. It is unquestionably the
most versatile PET around. It
wasn’t as much trouble as I orig-
inally anticipated, and I had fun
building it.

The real enjoyment comes
from using this disk system. I
have about 300 hours of use
with the new system and have
not had any problems. I have 12
diskettes full of programs or
files (approximately 960K of
storage) and have never lost a
bit. It is a pleasure to load a 16
or 24K program in less than
two seconds, or to see 20,830
bytes free after loading the disk
software. ■

118 Microcomputing January 1980

COmPUTBR Sf-/OPPSn

The Nationwide Marketplace for Computer Equipment

COMPUTER SHOPPER,
the first complete publication listing
business, commercial and personal computer equipment
is coming this fall with the type of information you can use
every month.

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system computers AND you can run YOUR FIRST CLASSIFIED
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advertising, including its flagship
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Using in-house computer facilities and professional type-
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modern techniques and large-space advertising to offset
normal costs.

EACH ISSUE OF COMPUTER SHOPPER GIVES YOU:

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• Categorized ads so you can find them instantly

• Large 11 by 14 easy -to-read format

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COMPUTER SHOPPER is YOUR place to buy or sell any computer
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To reach more than 20,000 computer-owning firms each month,
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EVEN A LIMITED-TIME COMPUTER USER can get any buy, sell
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O 305-269-3211, 8 a.m. - 5 p.m. ^ C168

LIST OF CATEGORIES IN COMPUTER SHOPPER

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TRS-80, Software, Peripheral
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Misc. Microcomputer Software,
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Peripheral & Misc. Equipment

Card Readers
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SPECIAL Charter Subscription OFFER
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Reader Service— see page 227

Microcomputing January 1980 119

SOFTWARE FOR 1980- AND BEYOND

A new decade begins! It is a time to take inventory of one’s past and
make resolutions for the future. Instant Software resolves to continue to
bring you new, exciting, and useful programs. The inventory of our past
accomplishments has now expanded to six pages. We have programs
for theTRS-80, Levels I and II; PET; Apple II; and Heath H-8. So ring in the
new with quality programs from

> TRS-80 <T

Level I and II

OIL TYCOON Avoid oil spills, blowouts and dry
wells as you battle to become the world’s richest
oil tycoon. Two players become the owners of
competing oil companies as they search for oil
and control their companies. Requires a TRS-80
4K Level I or II. Order No. 0023R $7.95.

HAM PACKAGE I This versatile package lets you
solve many of the problems commonly encoun-
tered in electronics design. With your Level I 4K
or Level II 16K TRS-80, you have a choice of:

• Basic Electronics with Voltage Divider -Solve
problems involving Ohm’s Law, voltage dividers,
and RC time constants.

•Dipole and Yagi Antennas- Design antennas
easily, without tedious calculations.

This is the perfect package for any ham or techni-
cian. Order No. 0007R $7.95.

ELECTRONICS I This package will not only
calculate the component values for you, but will
also draw a schematic diagram. You’ll need a
TRS-80 Level I 4K, Level II 16K to use:

•Tuned Circuits and Coil Winding- Design
tuned circuits without resorting to cumbersome
tables and calculations.

•555 Timer Circuits -Quickly design astable or
monostable timing circuits using this popular 1C.
•LM 381 Preamp Design- Design 1C preamps
with this low-noise integrated circuit.

This package will reduce your designing time
and let you build those circuits fast. Order No.
0008 R $7.95.

AIR FLIGHT SIMULATION Turn your TRS-80
into an airplane. You can practice takeoffs
and landings with the benefit of full in-
strumentation. This one-player simulation re-
quires a TRS-80 Level I 4K, Level II 16K. Order
No. 001 7R $7.95.

BEGINNER’S BACKGAMMON/KENO Why sit

alone when you can play these fascinating
games with your TRS-80?

•Backgammon -Play against the computer.
Your TRS-80 will give you a steady, challenging
game that’s sure to sharpen your skills.

•Keno— Enjoy this popular Las Vegas gambling
game. Guess the right numbers and win big.
You’ll need a TRS-80 Level I or II. Order No. 0004R
$7.95.

BOWLING Let your TRS-80 set up the pins and
keep score. One player can pick up spares and
get strikes. For the TRS-80 Level I 4K, Level II
16K. Order No. 0033R $7.95.

BUSINESS PACKAGE IV Business Package IV
gives you, the businessman, a superb tool to help
you make those important decisions. This pack-
age includes:

•Business Cycle Analysis -This program isn’t a
crystal ball, but it can show you your business’s
expansion and contraction cycles. You can plot
any aspect of your business on a graph and see,
in black and white, just what’s happening. This
program will give you access to information you
couldn’t get before.

• Financial Analysis -Would you like a financial
assistant who could instantly give you the fig-
ures for almost any kind of investment? Finan-
cial Analysis can handle annuities, sinking
funds, and mortgages, and compute bond yield
and value. You’ll have the facts you need at the
tips of your fingers with this program.

Included in the package is one specially
marked blank data cassette for use in storing
essential business data.

Business Package IV, with its combination of
analytic functions and convenience features, is
an invaluable asset for any businessman. All you
need is a TRS-80 Level I 4K or Level II 16K. Order
No. 001 9R $9.95.

GOLF/CROSS-OUT Have fun with these exciting
one-player games. Included are:

•Golf — You won’t need a mashie or putter — or a
caddie, for that matter — to enjoy a challenging
18 holes.

•Cross-out — Remove all but the center peg in
this puzzle, and your neighbors will call you a
genius.

You’ll need a TRS-80 Level I 4K, Level II 16K.

Order No. 0009R $7.95.

BASIC AND INTERMEDIATE LUNAR LANDER

Bring your lander in under manual control. The
BASIC version is for beginners; the Intermediate
version is more difficult, with a choice of landing
areas and rugged terrain. For one player with a
TRS-80 Level I 4K, Level II 16K. Order No. 0001 R
$7.95.

SPACE TREK II Protect the quadrant from the in-
vading Klingon warships. The Enterprise is
equipped with phasers, photon torpedoes, im-
pulse power, and warp drive. It’s you alone and
your TRS-80 Level I 4K, Level II 16K against the
enemy. Order No. 0002R $7.95.

Level I

CAVE EXPLORING/YACHT/MEMORY These
three programs are not only fun, but stimulating
as well:

•Cave Exploring — Search for fabulous treasures
as you explore the magic cave. For one player.
•Yacht -A two-player game of strategy and
chance. The computer rolls the dice and keeps
score.

•Memory - Two players can pit their memories in
this program based on a popular television show.
You’ll need a TRS-80 with Level I and 16K. Order
No. 001 OR $7.95.

CAR RACE/RAT TRAP/ANTIAIRCRAFT Enjoy
these challenging, fun-filled programs:

•Car Race -You and a friend can race on a
choice of two tracks.

•Rat Trap -Trap the rat in his maze with your two
cats. For one player.

•Antiaircraft — Aim and shoot down the enemy
airplane. Requires Level I 4K TRS-80. Order No.
001 1R $7.95.

KNIGHTS QUEST/ROBOT CHASE/HORSE RACE

This varied package of one-player games will
give you hours of fun.

•Knight’s Quest- Battle demons to gain
treasure and become a full-fledged knight.

• Robot Chase — Destroy the deadly robots
without electrocuting yourself.

•Horse Race — Place your bet and cheer your
horse to the finish line.

These programs require a TRS-80 Level I 4K.

Order No. 0003R $7.95.

STATUS OF HOMES/AUTO EXPENSES Two long-
awaited programs that have got to save you
money at work or in the home:

•Status of Homes -This program will allow you
to keep track of all the expenses involved in
building one house or an entire subdivision.
•Auto Expenses — Find out exactly what it costs
you to drive your car or truck.

These programs require a TRS-80 Level I 4K.
Order No. 001 2R $7.95.

DESTROY ALL SUBS/GUNBOATS/BOMBER This
package of three programs is fun for the whole
family. Included are:

• Destroy All Subs — Hunt down enemy subs
while avoiding mines and torpedoes. A one-
player game.

•Gunboats — Try to blow the enemy’s ship out of
the water. For one or two players.

• Bomber — Carefully release your bomb to
destroy the moving submarine. A one-player
game.

To enjoy these programs, you’ll need a TRS-80
Level I 4K. Order No. 0021 R $7.95.

Level I

BUSINESS PACKAGE I Keep the books for a
small business with your TRS-80 Level I 4K. The
six programs included are:

•General Information — The instructions for us-
ing the package.

•Fixed Asset Control —This will give you a list of
your fixed assets and term depreciation.

•Detail Input — This program lets you create and
record your general ledger on tape for fast ac-
cess.

•Month and Year to Date Merge -This program
will take your monthly ledger data and give you a
year to date ledger.

•Profit and Loss -With this program you can
quickly get trial balance and profit-and-loss
statements.

•Year-End Balance -This program will combine
all your data from the profit-and-loss statements
into a year-end balance sheet.

With this package, you can make your TRS-80 a
working partner. Order No. 001 3R $29.95.

BUSINESS PACKAGE III This package can
change your TRS-80 into a full working partner
for any businessman:

•Inventory — Maintain a computer-based inven-
tory for a constant inventory system.
•Commissions and Percentages - Let your com-
puter figure out markup and discount calcula-
tions, sales tax and more. This is a perfect time-
saving package for any small business.

For the TRS-80 Level I 4K. Order No. 0061 R $7.95.

DOODLES AND DISPLAYS I Here’s a mixed bag
of programs that’s sure to entertain:

•Doodle Pad — Draw pictures and save them on
cassette tapes.

•Symmetries — Turn your TRS-80 into a kaleido-
scope.

•Video Display — Follow the bouncing cursor as
your TRS-80 draws its own pictures.
•Mathcurves- Bring those geometry lessons to
life as the computer draws six different geomet-
rical curves.

•Rugpatterns- A never ending stream of sym-
metrical patterns that’s sure to spark your imag-
ination.

All you’ll need is a 16K Level I TRS-80. Order No.
0030R $7.95.

SPACE TREK III Let yourself go to the far ends of
the solar system -and beyond. This package in-
cludes:

•Stellar Wars — Shoot down the Tie fighters and
destroy the Death Star.

• Planetary Lander -Land your spacecraft and
plant your flag across the solar system.

These one-player games require a TRS-80 Level I

4K. Order No. 0031 R $7.95.

SPECIAL DELIVERY

OK, Ace, you survived everything that von Richthofen and the
Flying Circus threw at you. Well, that was four long years ago — and
yesterday’s medals don’t pay the rent. But just a minute, here’s an

ad-

“Airmail Pilot wanted . . .”

AIRMAIL PILOT

You can almost smell the gasoline as the ground crew fuels your J-4 Jenny
biplane to her 26-gallon limit. Precious mail is loaded into the cargo area, tagged
for Chicago. The weatherman reports severe icing above 6,000 feet, so you know
you have to keep the plane low. It will be a dangerous flight, but you knew that
when you took the job. The mail must go through. So, in the tradition of Lindbergh
and a hundred unsung heroes, you bravely turn your plane into the wind. The
engine roars. Suddenly you’re aloft on the first leg of your journey. Dayton’s
socked in by fog. You change your course for Lucasville. Lightning zigzags the sky.
A massive, fast-moving thunderstorm forces you to land in a cornfield. As the
weather clears, your plane leaps once more into the sky. But even clear skies can
cause problems — violent air currents buffet your fragile wooden aircraft. Your fuel
is down to two gallons as Lucasville comes into sight. You make it! Refuel and
head for Chicago. But you’re not out of trouble yet. There’s a wind shear at the
Chicago airport. You have to land in a shifting crosswind. Can you make it? AIR-
MAIL PILOT from INSTANT SOFTWARE. Unlike any other computer simulation
you’ve ever experienced. Challenging. Difficult. But never impossible. An event in a
cassette. Crash or fly, it’s so realistic, you can almost feel the wind. Requires a
Level II 16K. Order No. 0106R $7.95.

FUN PACKAGE I Why call it “Fun Package”?
Judge for yourself! This entertaining package in-
cludes:

• Rocket Pilot -Flying it is easy -it’s the landing
that’s tough!

•Paper, Rock, Scissors -It’s the time-honored
game just as you remember it, played against
your TRS-80.

• Hex I — Just when you master this puzzle game,
the computer will increase the difficulty.
•Missile Attack — Use your missiles to protect
your city from jet attack.

Requires a Level I 16K TRS-80. Order No. 0037R
$7.95.

TYPING TEACHER This complete seven-part
package takes you all the way from initial
familiarization with the keys, through typing
words and phrases, to complete mastery of the
keyboard. Your computer can even become a bot-
tomless page for typing practice. It only requires
a TRS-80 Level I 4K. Order No. 0099R $7.95.

PERSONAL FINANCE I Let your TRS-80 handle
all the tedious details the next time you figure
your finances:

•Personal Finance I — With this program you can
control your incoming and outgoing expenses.
•Checkbook — Your TRS-80 can balance your
checkbook and keep a detailed list of expenses
for tax time.

This handy financial control for the home re-
quires only a TRS-80 Level I 4K. Order No. 0027R
$7.95.

HEXPAWN/SHUTTLE CRAFT DOCKING/SPACE
CHASE/SEA BATTLE This four-game package is
sure to provide hours of fun for the whole family.
• Hexpawn — Turn your TRS-80 into a model of ar-
tificial intelligence by playing a simple game.
•Shuttle Craft Docking - Land your shuttle craft
on the starship -even through varying gravity
fields!

•Space Chase - Seek out and destroy the enemy
delta that’s hidden in the star field.

•Sea Battle — You must find and destroy the
enemy fleet.

This package requires a TRS-80 Level I 16K.

Order No. 0041 R $7.95.

DEMO I This package is just the thing to show
your friends what your TRS-80 can do. Included
are:

•Computer Composer — Compose and play
music using only a standard AM radio.

• Baseball -Play baseball with your computer
while it does the scorekeeping.

• Horse Race -Place your bet and cheer your
pony to the winner’s circle.

•ESP - Test your powers of extrasensory percep-
tion.

•Hi-LorTic-tac-toe — Guess the secret number or
get three in a row.

•Petals Around the Rose - Can you figure out the
secret behind the five dice?

•Slot Machine -Turn your computer into a one-
armed bandit. These programs require a TRS-80
Level I 4K. Order No. 0020R $7.95.

Level II

TRS-80 UTILITY I Ever wonder how some pro-
grammers give their programs that professional
look? Instant Software has the answer with the
TRS-80 Utility I package. Included are:

• RENUM — Now you can easily renumber any
Level II program to make room for modification
or to clean up the listing.

•DUPLIK-This program will let you duplicate
any BASIC, assembler, or machine-language pro-
gram, verify the data, and record the program on
tape. You can even do Level I programs on a
Level II machine. For the TRS-80 Level II 16K.
Order No. 0081 R $7.95.

0100R ln *** n * Software Ine PMaiVorough NM CH5B US* srt motto lot program mtormtooo

VIDEO SPEED-READING TRAINER As your
eyes move along, reading this sentence, do
you see the words like this? Most peo-
ple’s reading speed is limited simply because
they read individual letters or words. Now you
can increase your reading speed and com-
prehension, and soon be reading whole
words and phrases, with the Video Speed-
Reading Trainer package from Instant Soft-
ware.

Using the same scientific principle as the
tachistoscope, a mechanical device used to
flash characters or words on a screen, this
three-part program will train your mind to
quickly recognize numbers, words, letters,
and phrases.

The program will take you step by step
through a systematic training procedure.
You’ll start at whatever level of competency
you feel is appropriate, and the computer will
automatically advance you as your reading
speed and comprehension increase. For the
Level II 16K TRS-80 Microcomputer. Order
No. 0100R $7.95.

DEMO II Now get more fun for the bucks with this
amazing package.

•Tlc-Tac-Toe-Play an old-time favorite with
three levels of difficulty.

•Time Trials -Try to beat the clock as you race
your car through curves, chutes, and chicanes.

• Maze — One or two players can search through
the maze for the secret square.

• Hangman — One or two players can try to guess
the secret word.

•Wheel of Fortune -Choose your number, place
your bet, and see if you can break the bank (for
one to eight players).

•Hurricane- Now you can track and monitor
hurricanes anywhere in the world.

•Bugsy — Can you build your Z-80 bug before the
computer does?

•Horse Race - Pick a sure winner and place your
bet (for 1 to 100 players).

All you’ll need is a TRS-80 Level II 16K. Order No.
0049 R $7.95.

RAMROM PATROL/TIE FIGHTER/KLINGON
CAPTURE Buck Rogers never had it so good.
Engage in extraterrestrial warfare with:

•Ramrom Patrol -Destroy the Ramrom ships
before they capture you.

•Tie Fighter -Destroy the enemy Tie fighters
and become a hero of the rebellion.

• Klingon Capture- You must capture the Kling-
on ship intact. It’s you and your TRS-80 Level II
16K battling across the galaxy. Order No. 0028R
$7.95.

DOODLES AND DISPLAYS II Wait until your
children get hold of this package:

• Doodle Pad — Draw pictures and save them on
cassette tapes.

•Symmetries — An electric kaleidoscope that
changes from black to white and back again. It’s
almost hypnotic!

• Drawing — Like Doodle Pad, but for the serious
artist. Over 40 user commands!

• Random Pattern Display -The computer does
the drawing, but those with itchy fingers can
tamper.

• Mathcurves- Bring those geometry lessons to
life. Six different geometrical curves on the
screen of your TRS-80.

• Rugpatterns — Yes, it does design rug patterns;
and with a choice of user or computer control, it
can do a whole lot more.

For the Level II 16K TRS-80. Order No. 0042R
$7.95.

DEMO III This is the biggest package that Instant
Software has ever released. Just look at what’s
included:

• Race 1 - Careen around the race course as you
try to beat the clock.

•Target UFO -Destroy all the invading UFOs to
rack up a big score.

•Life -Experiment with this simulation of the
life cycle of a colony of bacteria.

• Phone Number Converter -Change those hard-
to-remember 7-digit phone numbers into easily
remembered words.

•Biorhythm -You or your friends can see your
biorhythm curves whenever you want.

•Graphics Program -This program will really
show you what your TRS-80’s graphics display
can do.

• Race 2 — Our racing game simulation for the
more experienced driver includes a choice of five
different tracks.

•Horse Race - Up to nine players can bet on and
enjoy our most entertaining horse race program.
•Drawing Board — Draw pictures or messages
and store them in memory or on cassette tape
with this easy-to-use program.

•24-Hour Clock — Transform your computer into
an accurate digital clock.

To enjoy this tremendous value, you’ll need a
TRS-80 Level II 16K. Order No. 0055R $7.95.

HOUSEHOLD ACCOUNTANT Let your TRS-80
help you out with many of your daily household
calculations. Save time and money with these
fine programs:

• Budget and Expense Analysis — You can

change budgeting into a more pleasant job with
this program. With nine sections for income and
expenses and the option for one- and three-
month review or year totals, you can see where
your money is going.

•Life Insurance Cost Comparison - Compare the
costs of various life insurance policies. Find out
the difference in price between term and whole
life. This program can store and display up to six
different results.

All you need is TRS-80 Level II 16K. Order No.
0069 R $7.95.

FINANCIAL ASSISTANT Compute the figures for
a wide variety of business needs. Included are:
•Depreciation -This program lets you figure
depreciation on equipment in five different ways.
•Loan Amortization Schedule -Merely enter a
few essential factors, and your TRS-80 will
display a complete breakdown of all costs and
schedules of payment for any loan.

• Financier-This program performs thirteen
common financial calculations. Easily handles
calculations on investments, depreciation, and
loans.

•1% Forecasting -Use this simple program to
forecast sales, expenses, or any other historical
data series.

All you need is a TRS-80 Level II 16K. Order No.
0072R $7.95.

MODEL ROCKET ANALYZER AND PRE-FLIGHT
CHECK Let your TRS-80 help you enjoy the fast-
growing hobby of model rocketry. The comple-
mentary programs included are:

•Model Rocket Flight History Prediction -This
program will compute the flight characteristics
for almost any model rocket. Engine and body
tube data included covers Estes, Centuri, Flight
Systems, A.V.I. Astroport, C.M.R., and Kopter
products.

• Weather Forecaster- Before you launch your
rocket, get an up-to-the-minute weather forecast.
Just enter your location, elevation, average
temperatures for January and July, and baromet-
ric pressure. You’ll be the short-range weather
forecaster for your area.

For a successful launch, you’ll need TRS-80
Level II 16K. Order No. 0024R $7.95.

CARDS This one-player package will let you play
cards with your TRS-80 — tal k about a poker face !

• Draw and Stud Poker-These two programs will
keep your game sharp.

•No-Trump Bridge — Play this popular game with
your computer and develop your strategy.

This package’s name says it all. Requires a
TRS-80 Level II 16K. Order No. 0063R $7.95.

PERSONAL BILL PAYING

NOTE: This package can take the head-
aches and/or penalties out of paying your
bills.

In a business office the accounts payable
(bills) are usually paid on or immediately before
their due date. That way, the payer gets the
fullest use of his money without incurring
penalties for being behind in paying his debts.
Now you can take advantage of this system for
your monthly bills, letting your TRS-80 do all the
drudgery and record keeping.

This useful package provides a computerized
list of all your bills and payments. You can ac-
cess as many as 22 accounts, all of which can be
named -up to 15 characters per name. Each ac-
count is listed by number, amount owed, due
date, and present activity.

Don’t confuse this system with a “checkbook”
program. The functions of this package are
threefold: (1) to monitor your bills; (2) to order
payments most effectively; and (3) to make
historical comparisons of individual accounts or
specific months.

After you load the program, it displays a menu
of 11 activities. They include:

Build and Maintain Files
List All Accounts
List Current Accounts
Make Payment(s) to Account
Enter New Bill to Account
Display Payment History of Individual Ac-
count (includes date paid, check number, and
12-month total)

Display Payment History of Selected Month

Delete Account

Delete Prior Month’s Payment

Save File on Tape

Input File from Tape

After you have updated the records by entering
new bills, paying bills, or changing the accounts,
you can save all the information on data tape.
This data tape will then be input for the next time
you use the package. Maybe it can’t make paying
bills all fun and games, but it should relieve some
of the agony. Level II 16K required. Order No.
0103R $7.95.

Level II

SPACE TREK IV Trade or wage war on a
planetary scale. This package includes:

•Stellar Wars - Engage and destroy Tie fighters
in your attack on the Death Star. For one player.
• Population Simulation -A two-player game
where you control the economy of two neighbor-
ing planets.

You decide, guns or butter, with your TRS-80
Level II 16K. Order No. 0034R $7.95.

TEACHER Now you can have the benefits of
computer-assisted instruction right in your own
home. The programs allow you to input any
number of questions and answers. Using this
data, the computer will prepare several types of
tests, quiz students, provide up to three “hints”
per question -even offer graphic rewards for
younger children, all at the user’s discretion.
Perfect for parents, teachers, or anyone faced
with learning a lot of material in the shortest
possible time. Furnished with blank data
cassette.

Teacher requires a 16K Level II TRS-80. Order No.
0065 R $9.95.

TRS-80 UTILITY II Let Instant Software change
the drudgery of editing your programs into a
quick, easy job. Included in this package are:
•CFETCH- Search through any Level II program
tape and get the file names for all the programs.
You can also merge BASIC programs with con-
secutive line numbers into one program.
•CWRITE- Combine subroutines that work in
different memory locations into one program.
This works with BASIC or machine-language pro-
grams and gives you a general checksum.

This package is just the thing for your TRS-80
Level II 16K. Order No. 0076R $7.95.

Santa Paravia
and Fiumaccio

Buon giorno, signore!

Welcome to the province of Santa
Paravia. As your steward, I hope
you will enjoy your reign here. I
feel sure that you will find it, shall
we say, profitable.

Perhaps I should acquaint you with our little domain. It is
not a wealthy area, signore, but riches and glory are possi-
ble for one who is aware of political realities. These realities
include your serfs. They constantly request more food from
your grain reserves, grain that could be sold instead for gold
florins. And should your justice become a trifle harsh, they
will flee to other lands.

Yet another concern is the weather. If it is good, so is the
harvest. But the rats may eat much of our surplus, and we
have had years of drought when famine threatened our
population.

Certainly, the administration of a growing city-state will
require tax revenues. And where better to gather such funds
than the local marketplaces and mills? You may find it
necessary to increase custom duties as well as tax the incomes of the mer-
chants and nobles. Whatever you do, there will be far-reaching conse-
quences . . . and possibly an elevation of your noble title.

Your standing will surely be enhanced by building a new palace, or
perhaps a magnificent cattedrale. You will do well to increase your lan-
dholdings, if you also equip a few units of soldiers. There is, alas, no small
need for soldiery here, for the crafty Baron Peppone may invade you at any
time.

To measure your yearly progress, the official mapmaker will draw you a
mappa. From it you can see how much land you hold, how much of it is
under the plow, and how adequate your defenses are. We are unique in that
here, the map IS the territory.

I trust that I have been of help, signore. I look forward to the day when I
may address you as His Royal Highness, King of Santa Paravia. Buon for -
tuna , or, as you say, “Good luck.” For the TRS-80 Level II 16K. Order No.
0043 R $7.95.

> PET"

PERSONAL WEIGHT CONTROL/BIORHYTHMS

Let your PET help take care of your personal
health and safety:

• Personal Weight Control - Your PET will not on-
ly calculate your ideal weight, but also offer a
detailed diet to help control your caloric intake.
•Biorhythms — Find out when your critical days
are for physical, emotional, and intellectual
cycles.

You’ll need only a PET with 8K memory. Order
No. 0005 P $7.95.

CASINO I These two programs are so good, you
can use them to check out and debug your own
gambling system!

•Roulette - Pick your number and place your bet
with the computer version of this casino game.
For one player.

•Blackjack -Try out this version of the popular
card game before you go out and risk your money
on your own “surefire” system. For one player.
This package requires a PET with 8K. Order No.
001 4P $7.95.

MORTGAGE WITH PREPAYMENT OPTION/FI-
NANCIER These two programs will more than
pay for themselves if you mortgage a home or
make investments:

•Mortgage with Prepayment Option -Calculate
mortgage payment schedules and save money
with prepayments.

• Financier- Calculate which investment will
pay you the most, figure annual depreciation,
and compute the cost of borrowing, easily and
quickly.

All you need to become a financial wizard with an

8K PET. Order No. 0006P $7.95.

CASINO II This craps program is so good, it’s the
next best thing to being in Las Vegas or Atlantic
City. It will not only play the game with you, but
will also teach you how to play the odds and
make the best bets. A one-player game, it re-
quires a PET 8K. Order No. 001 5P $7.95.

TREK-X Command the Enterprise as you scour
the quadrant for enemy warships. This package
not only has superb graphics, but also includes
programming for optional sound effects. A one-
player game for the PET 8K. Order No. 0032P
$7.95.

CHECKERS/BACCARAT Play two old favorites
with your PET.

•Checkers — Let your PET be your ever-ready op-
ponent in this computer-based checkers pro-
gram.

• Baccarat -You have both Casino- and Black-
jack-style games in this realistic program.

Your PET with 8K will offer challenging play
anytime you want. Order No. 0022P $7.95.

DOW JONES Up to six players can enjoy this ex-
citing stock market game. You can buy and sell
stock in response to changing market condi-
tions. Get a taste of what playing the market is
all about. Requires a PET with 8K. Order No.
0026P $7.95.

TANGLE/SUPERTRAP These two programs re-
quire fast reflexes and a good eye for angles:
•Tangle -Make your opponent crash his line in-
to an obstacle.

•Supertrap — This program is an advanced ver-
sion of Tangle with many user control options.
Enjoy these exciting and graphically beautiful
programs. For one or two players with an 8K PET.

Order No. 0029P $7.95.

> PET

• * *

MIMIC Test your memory and reflexes with the
five different versions of this game. You must
match the sequence and location of signals
displayed by your PET. This one-player program
includes optional sound effects with the PET 8K.
Order No. 0039P $7.95.

PENNY ARCADE Enjoy this fun-filled package
that’s as much fun as a real penny arcade — at a
fraction of the cost!

•Poetry -Compose free verse poetry on your
computer.

•Trap — Control two moving lines at once and
test your coordination.

•Poker- Play five-card draw poker and let your
PET deal and keep score.

•Solitaire -Don’t bother to deal, let your PET
handle the cards in this “old favorite” card game.
• Eat-Em-Ups-Find out how many stars your
Gobbler can eat up before the game is over.
These six programs require the PET with 8K.
Order No. 0044P $7.95.

ARCADE II One challenging memory game and
two fast-paced action games make this one
package the whole family will enjoy for some
time to come. Package includes:

•UFO — Catch the elusive UFO before it hits the
ground!

• Hit- Better than a skeet shoot. The target re-
mains stationary, but you’re moving all over the
place.

•Blockade — A two-player game that combines
strategy and fast reflexes.

Requires 8K PET. Order No. 0045P $7.95.

BASEBALL MANAGER This pair of programs will
let you keep statistics on each of your players.
Obtain batting, on-base, and fielding averages at
the touch of a finger. Data can be easily stored
on cassette tape for later comparison. All you
need is a PET with 8K. Order No. 0062P $14.95.

ACCOUNTING ASSISTANT This package will
help any businessman solve many of those
day-to-day financial problems. Included are:
•Loan Amortization Schedule - This program
will give you a complete breakdown of any
loan or investment. All you do is enter the
principal amount, interest rate, term of the
loan or investment, and the number of
payments per year. You see a month-by-
month list of the principal, interest, total
amount paid, and the remaining balance.
•Depreciation Schedule — You can get a de-
preciation schedule using any one of the
following methods: straight line, sum of
years-digits, declining balance, units of pro-
duction, or machine hours. Your computer
will display a list of the item's lifespan, the
annual depreciation, the accumulated depre-
ciation, and the remaining book value. This
package requires the PET 8K. Order No.
0048 P $7.95.

DIGITAL CLOCK Don’t let your PET sit idle when
you are not programming — put it to work with
these two unique and useful programs:

• Digital Clock -Turn you PET into an extremely
accurate timepiece that you can use to display
local time and time in distant zones, or as a split-
time clock for up to nine different sporting
events.

• Moving Sign — Let the world know what’s on
your mind. This program turns your PET into a
flashing graphic display that will put your
message across. Order No. 0083P $7.95.

DECORATOR’S ASSISTANT This integrated set
of five programs will compute the amount of
materials needed to redecorate any room, and
their cost. All you do is enter the room dimen-
sions, the number of windows and doors, and the
base cost of the materials. These programs can
handle wallpaper, paint, panelling, and carpet-
ing, letting you compare the cost of different
finishing materials. All you’ll need is a PET 8K.
Order No. 0104P $7.95.

DUNGEON OF DEATH Battle evil demons, cast
magic spells, and accumulate great wealth as
you search for the Holy Grail. You’ll have to de-
scend into the Dungeon of Death and grope
through the suffocating darkness. If you survive,
glory and treasure are yours. For the PET 8K.
Order No. 0064P $7.95.

ARCADE I This package combines an exciting
outdoor sport with one of America’s most pop-
ular indoor sports:

•Kite Fight -It’s a national sport in India. After
you and a friend have spent several hours
maneuvering your kites across the screen of your
PET, you’ll know why!

•Pinball -By far the finest use of the PET’S ex-
ceptional graphics capabilities we’ve ever seen,
and a heck of a lot of fun to boot.

Requires an 8K PET. Order No. 0074P $7.95.

TURF AND TARGET Whether on the field or in the
air, you’ll have fun with the Turf and Target
package. Included are:

•Quarterback - You’re the quarterback as you try
to get the pigskin over the goal line. You can
pass, punt, hand off, and see the result of your
play with the PET’s superb graphics.

•Soccer II - Play the fast-action game of soccer
with four playing options. The computer can play
itself or a single player; two can play with com-
puter assistance, or two can play without help.
•Shoot — You’re the hunter as you try to shoot the
bird out of the air. The PET will keep score.
•Target — Use the numeric keypad to shoot your
puck into the home position as fast as you can.
To run and score, all you’ll need is a PET with 8K.
Order No. 0097P $7.95.

Apple <(

GOLF Without leaving the comfort of your chair,
you can enjoy a computerized 18 holes of golf
with a complete choice of clubs and shooting
angles. You need never cancel this game be-
cause of rain. One or two players can enjoy this
game on the Apple with Applesoft II and 20K.
Order No. 001 8A $7.95.

BOWLING/TRILOGY Enjoy two of America’s
favorite games transformed into programs for
your Apple:

• Bowling - Up to four players can bowl while the
Apple sets up the pins and keeps score. Requires
Applesoft II.

•Trilogy -This program can be anything from a
simple game of tic-tac-toe to an exercise in
deductive logic. For one player.

This fun-filled package requires an Apple with

20 K. Order No. 0040A $7.95.

MATH TUTOR I Parents, teachers, students, now
you can turn your Apple computer into a math-
ematics tutor. Your children or students can
begin to enjoy their math lessons with these pro-
grams:

• Hanging- Perfect your skill with decimal
numbers while you try to cheat the hangman.
•Spellbinder- Cast spells against a competing
magician as you practice working with fractions.
•Whole Space -While you exercise your skill at
using whole numbers, your ship attacks the
enemy planet and destroys alien spacecraft.

All programs have varying levels of difficulty. All
you need is Applesoft II with your Apple II 24K.
Order No. 0073A $7.95

MORTGAGE WITH PREPAYMENT OPTION/FIN-
ANCIER (see description for PET version 0006P)
This package requires the Apple 16K. Order No.
0094A $7.95.

ACCOUNTING ASSISTANT (see the description
for the PET version 0048P) This package requires
the Apple 16K. Order No. 0088A $7.95.

MATH TUTOR II Your Apple computer can go •Robot Duel - Practice figuring volumes of
beyond game playing and become a mathe- various containers while your robot fights
matics tutor for your children. Using the tech- against the computer’s mechanical man.
nique of immediate positive reinforcement, you *Sub Attack -Take the mystery out of working
can make math fun with: with percentages as your submarine sneaks into

•Car Jump -Reinforce the concept of calculat- the harbor and destroys the enemy fleet,
ing area while having fun making your car jump All you need is Applesoft II with your Apple II and
over the ramps. 20K. Order No. 0098A $7.95.

MIMIC (see description for the PET version
0039 P) This package requires the Apple 24K.

Order No. 0025A $7.95.

> HEATH <

MENTAL GYMNASTICS Pit your mind against
the challenge of these ancient games:

•Reversi — As you and a friend or the computer
place your pieces on the board, you must each
try to capture your opponent’s pieces. The score
can fluctuate wildly, and nobody can tell who’ll
win until the last move.

•Wall — You can play a friend or the computer in
this simple yet intriguing game. The two players
take turns removing pieces from one cup and
placing them in the other cups. As play con-
tinues, the number of pieces decreases. The last
player who has a piece to move wins the game.
To enjoy these ageless games, you’ll need the
Heath H-8 with 8K. Order No. 0087H $7.95.

DATA TAPES Use these high-quality leaderless
data tapes to record business or personal data.
Four tapes per package. Order No. 0067 $7.95.

*A trademark of Tandy Corporation
An trademark of Commodore Business Machines, Inc.
** *A trademark of Apple Computer, Inc.

****A trademark of the HEATH Company

Ask for Instant Software at a computer store near you.

Alabama

Anderson Computers

3156 University Dr„ Huntsville

The Computer Shack

913 Shadyview Lane. Adamsville

Computerland of Huntsville

3020 University Dr.. Huntsville

Olensky Bros.

3763 Airport Blvd.. Mobile

Arizona

Millets TV & Radio

621 East Broadway. Mesa

Resalem Electronics

16610 Meadow Park Dr.. Sun City

California

Amco Elect. Supply
635 E. Arrow Hwy., Azusa

Byte Shop of Fairfield

87 Marina Center St.. Suisun City

Byte Shop of Mt. View

1415 West El Camino Real. Mt. View

Byte Shop of Sacramento

6041 Greenback Ln.. Citrus Heights

Capital Computer Systems

3396 El Camino Ave., Sacramento

Computer Components of South Bay

15818 Hawthorne Blvd., Lawndale

Computer World

6791 Westminster Ave., Westminster
Computerland

16720 S. Hawthorne, Lawndale
Computerland of San Francisco
117 Fremont St., San Francisco

Computerland of W. LA

6840 La Cienega Blvd., Englewood

Hobby World

19511 Business Ctr. Dr., Unit 6

Borthridge

I.C.E. House Inc.

398 North E. St., San Bernardino
Marfam Co.

6351 Almadin Rd., San Jose

Microsun Computer Center

2989 North Main St.. Walnut Creek

Opamp/Technical Books

1033 N. Sycamore Ave., Los Angeles

Radio Shack Dealer
8250 Mira Mesa Blvd.. San Diego
Santa Rosa Computer Center
604 7th St., Santa Rosa
Silver Spur Elect. Comm.

13552 Central Ave., Chino

The Computer Store

820 Broadway. Santa Monica

Colorado

Byte Shop

3464 S. Acoma St., Englewood
Computerland of North Denver
8749 Wadsworth Blvd., Arvada
The Computer Store
2300 Welton St., Denver

Connecticut

American Business Computers
Rt. 184 & Rt. 117, Groton
Bridgeport Computers Inc.

3876 Main St., Bridgeport
Computerlab

130 Jefferson, New London
Customized Computer Systems
120 Sherman Ave., New Haven
The Computer Store
43 South Main St., Windsor Locks

D.C.

The Program Store
4200 Wisconsin Ave., N.W.,
Washington. D.C.

Florida

AMF Electronics

11146 N. 30th St., Tampa

Boyd-Ebert Corporation

1328 West 15th St., Panama City

Computer Center

6578 Central Ave.. St. Petersburg

Computerland of Ft. Lauderdale

3963 N. Federal Hwy., Ft. Lauderdale

Curtis Waters Enterprises

236 Talbot Ave., Melbourne

Heath Kit Electronic

4705 W. 16th Ave. Center, Hialeah

Sound Ideas

220 1 C N.W. 13th, Gainesville
Ukatan Computer Store
Airport Rd., Destin

Georgia

Atlanta Computer Mart
Atlanta

Computerland of Atlanta
2423 Cobb Parkway, Smyrna

Hawaii

Computerland of Hawaii
567 N. Federal Hwy.

Radio Shack Assoc. Store
1712 S. King St., Honolulu

Idaho

Electronic Specialists
8411 Fairview Ave.. Boise

Illinois

Bloomington Normal Computer
Works

124 E. Beaufort, Normal
Computer Station
3659 Nameoki Rd.. Granite City
Midwest Micro Computers, Inc.

708 S. Main St., Lombard

Indiana

Computer Center of South Bend
51591 US 31 North. South Bend

Iowa

Memory Bank

4128 Brady St., Davenport

Louisiana

Computer Shoppe Inc.

3225 Danny Park, Suite 222, Metairie

Maryland

Computers, Etc.

13 A. Allegheny Ave., Towson
Jack Fives Electronics

4608 Debilen Circle, Pikesville

The Comm Center

9624 Ft. Meade Rd., Laurel

Massachusetts

Computer Packages Unlimited
244 W. Boylston St., West Boylston
Lighthouse Computer Software

14 Fall River Ave., Rehobath
New England Electronics Co.

679 Highland Ave., Needham
The Computer Store

120 Cambridge St.. Burlington
Tufts Radio & Electronics
206 Mystic Ave., Medford

Michigan

Computerland of Grand Rapids
2927 28th St. S.E., Kentwood

Computerland of Rochester
301 S. Livernois, Rochester

Computerland of Southfield
29673 Northwestern Hwy., Southfield

Computer Mart

560 W. 14 Mile Rd.. Clawson

Hobby House

1035 W Territorial Rd., Battle Creek

Minnesota

Zim Computers

5717 Xerxes Ave., N. Brooklin Center

Missouri

Computervan, Inc.

51 Florissant Oaks Shopping Center,
Florissant

Consolidated Software
16501 Greenwald Court, Belton

Montana

Intermountain Computer
529 So. 9th St., Livingston
The Computer Store
1216 16th St. W. #35. Billings

Nebraska

Computerland of Omaha
11031 Elm St., Omaha
Omaha Computer Store
4540 S. 84th St., Omaha

Nevada

Century 23

4566 Spring Mountain Rd.. Las Vegas

Home Computers

1775 Tropicana #2, Las Vegas

New Hampshire

Computerland of Nashua
419 Amherst St., Nashua
Radio Shack Assoc. Stores
31 Raynes Ave.. Portsmouth

New Jersey

Computer Encounter
2 Nassau St., Princeton
Radio Shack/J&J Electronic
Mansfield Shopping Ctr.

Rt. 57 Allen Rd., Hackettstown
The Computer Emporium
Bldg. 103, Avenues of Commerce
2428 Route 38. Cherry Hill
The Bargain Brothers
Glen Roc Shopping Center
216 Scotch Road. Trenton

New Mexico

South West Computer Center
121 Wyatt Drive, Suite 7. Las Cruces

New York

Aristo Craft

314 Fifth Ave., NYC

Automatic Systems Developers

Industry St., Poughkeepsie

Computer Corner

200 Hamilton Ave., White Plains

Computer Factory

485 Lexington Ave.. NYC

Computer House. Inc.

721 Atlantic Ave., Rochester
Comtek Electronics, Inc.

2666 Coney Island Ave..

Brooklyn

Comtek Electronics. Inc.

Staten Island Mall
Store 220A, Staten Island

Home Computer Center
671 Monroe Ave., Rochester
Key Electronics
Schenectady
Mr. Computer

Imp. Plaza, Rte 9, Wappingers Falls
The Computer Tree Inc.

409 Hooper Rd., Endwell

North Carolina

Byte Shop of Raleigh

1213 Hillsborough St., Raleigh

Ohio

Astro Video Electronics
504 E. Main St., Lancaster
Computerland

1288 Som Rd., Mayfield Heights
Computer Store of Toledo
18 Hillwyck Dr., Toledo
Forbees Microsystems Inc.

35 N. Broad, Fairborn
Heath Kit Co.

2500 Morst Rd., Columbus
Micro-Mini Computer World
74 Robinwood, Columbus
21st Century Shop
16 Convention Way, Cincinnati

Oregon

Computerland of Portland
12020 S.W. Main St.. Tigard

Pennsylvania

Artco Elect.

302 Wyoming Ave., Kingston
Artco Elect.

Back Mountain Shop. Ctr.,
Shavertown

Computerland of Harrisburg
4644 Carlisle Pike. Mechanicsburg
Erie Computer Co.

1253 West 8th St.. Erie
Personal Computer Corp.

24-26 West Lancaster Ave., Paoli
Personal Computer Corp.

Frazer Mall. Lancaster Ave., Frazer
The Computer Workshop of
Pittsburgh

4170 William Penn Hwy.. Murrysville
Wes Fasnacht

8 York Town Ave., West Chester

South Carolina

Seely Communications
1084 Broad St.. Sumter

South Dakota

CB Radio Shack

21st and Broadway. Yankton

Tennessee

Computerlab

671 S. Menden Hall Rd.. Memphis

Texas

Computercraft Inc.

3211 Fondren, Houston
Computer Port
926 N. Collig, Arlington
Houston Microcomputer Tech.

5313 Bissonet, Bell Aire
Interactive Computers
7620 Dashwood Rd., Houston
K.A. Elect.

9090 Stemmons Frwy., Dallas
Pan American Elect. Inc.

1117 Conway. Mission

Ram Micro Systems

6353 Camp Bowie Blvd.. Ft. Worth

Reb’s Mail Order Electronics
5439 Doliver, Houston

Virginia

Home Computer Center
2927 Virginia Beach Blvd.,

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Unleash your PET in the darkroom.

Jeff Knapp
1823 7th Ave.
Charleston WV 25302

the process control routine for
film and print developing; and
the clock/timer routine, which is
called by the exposure and pro-
cess routines. All the routines

make extensive use of the PET
BASIC GET command and the
PET’s real-time clock.

The control routine contained
in lines 130-230 GETS the menu

choice and sends you to the ap-
propriate section of the pro-
gram. As in all sections, the GET
command is used for menu
choices so you do not have to

M any people who have com-
puters and electronics for
hobbies or vocations also enjoy
another technical field, pho-
tography. This program for the
PET allows you to combine the
two fields to give you a practical
application for the computer
and, in addition, bring comput-
er accuracy to the darkroom.

Darkroom Master will let you
automate many of the timing
functions in your black-and-
white or color darkroom. With it
you can control your enlarger
and safelight for exposure and
sequentially time the process-
ing of your film, prints or slides.

The Software

There are four major sections
to the software: the control rou-
tine, containing a menu of avail-
able functions (each function
also has its own menu); the ex-
posure control routine for en-
larger and safelight operations;

Darkroom Master.

>oooooooo<><>oooooooooo

DARKROOM MASTER
BY JEFF KNAPP

16 REMOOOOOOOOCX

20 REM
30 REM
40 REM
50 REM
60 REM
70 REM
80 REM

30 R£M<XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX>

1 00 P0KE53459 , 255 • P0KE5347 1 , 0 ; D I MP$ < 6 >

1 10 r$( i >=”»flHwr p$ ■ fscs>=- ammmmw ■■

120 P$ < 5 ) = " fifBUftWlIlIllFlFWslBMBllW" : P$<6>= "

130 REM*********** TITLE PAGE

140 PR I NT "D "

150 PRINT” a DARKROOM MASTER

160 PRINTP$<2);TAE<4>; "PRESS . FOR
170 PRINTP*<3);TAB<4>; "PRESS - FOR
1 30 GETC* ; IFC$=" " THENG0T0 1 30
200 IFC$=". "THENGOSUB 250 GOTO 280
210 I FC*= " - ” THENGOT 0 640
230 GOTO 140

240 REM***:**** EXPOSURE CONTROL ROUTINE

250 PRINT ”13” ; TABC8); "

260 PRINT" a EXPOSURE CONTROL

270 RETURN

EXPOSURE CONTROL"
PROCESS CONTROL"

280 PRINTP*<1);TAB<4); "PRESS .
230 PRINTP*<2>;TAB(4); "PRESS -
300 PRINTP*<3>,TAB(4>; "PRESS =
310 GETA$ : IFA*=" "THENG0T0 310
320 IFA$=". "THENGOTG 360
330 IFA$="- ,, THENG0T0 460
340 GOTO 140

350 REM****** FOCUS ROUTINE
360 GOSUB 250
370 P0KE59471 > 16
380 PRINTP$< 1);TAB<4>;"

390 PRINTP*<2> ; TAB<4) ; "PRESS -

400 PRINTP$<3>;TAB<4>; "PRESS =

410 GETA* ; IFA*=" "THENG0T0 410

420 P0KE59471 , 0

430 I FAS="-" THENGOTG 460

440 GOTO 140

450 REM****** EXPOSURE ROUTINE

TO FOCUS"

TO SET EXPOSURE TIME"
TO START OVER"

TO SET EXPOSURE TIME"
TO START OVER"

126 Microcomputing January 1980

press the return key to activate
the PET.

If you press the “start over”
key or any illegal key, the PET
will cancel the function and
send you back to the control
routine. All of the control keys
are located at the bottom of the
numeric keypad, with the excep-
tion of the space key (more
about that later), so that it is
easy to make entries without
hunting all over the keyboard in
the dark and possibly pressing
the wrong button.

The exposure control routine,
lines 240-630, consists of two
subroutines for focusing and
obtaining the actual exposure.
Each has its own menu of op-
tions. The focus subroutine only
turns on the enlarger; no timing
is performed here. But the expo-
sure subroutine, once it inputs
your exposure time, calls the
clock/timer and turns off the
safelight, turns on the enlarger
and starts counting until the
clock matches your entry. Then
it shuts down the enlarger and
turns the safelight back on.

You now have the option of
exposing another print (if you
want to make 100 prints from
the same negative), changing
your exposure time, refocusing
the enlarger or starting over
from control and going on to
process your print.

The process control routine,
lines 640-1090, as written, is set
up for processing black-and-
white prints. I'll talk later about
setting it up for processing films
and color media. Upon going to
the routine from control, you will
be asked to enter times for
developing, stop-bath time, fix
time and the drain times in be-
tween steps. You can change
your times once they are en-
tered if you wish.

When you start the timing,
each step is printed on the
screen along with its own clock
in reverse video. At the end of
the timing sequence, you are
asked if you want to run the
same times again for proces-
sing the 100 prints you made
earlier.

The clock/timer routine, lines
1100-1270, is the heart of the
program. It compares your entry
against the current time and
takes appropriate action on the

460 GOSUB 250
470 PRINTP$a),TAB<21>;"

480 PRINTP$a>; PRINTTflB<8>;

490 PRINTP$<3>;TflB<4); "PRESS
500 PRINTP$<4) ; TRB<4) ; "PRESS
518 PRINTP$<5); TAB<4); "PRESS
520 PRINTP$<6) , TAB<4) ; "PRESS
530 GETR$ : I FR$="" THENGOTO 530
540 IFA$="0"GOTO 586
550 IFH*=". "GOTO 470

560 I FR$= " - " THENP0KE5947 1 .• 0 ; G0SUB 250 : GOTO 370

INPUT "EXPOSURE TIME" ;ET$

0 TO START/REPEAT EXPOSURE"
. TO CHANGE EXPOSURE"

- TO FOCUS"

= TO START OVER"

570 GOTO 140

580 TM$=ET*:P=1 :T=21:TI*= "O00000"

590 P0KE59471,16
600 GOSUB 1100
610 POKE59471,0
620 GOTO 490
630 STOP

640 REM###### PROCESS CONTROL ROUTINE

650 DT$="0" : BR$*"0" : ST$*"0" :FT*="0" WT$="0" POKE59471,0

660 PR I NT '73 "

670 PRINT" U PROCESS CONTROL "

680 PRINTP*<1>;TAB<7>:INPUT"DEVEL0P TIME ";BT*

690 PRINTP* <2>, TRB<6) : INPUT "ST0PBATH TIME ",ST*

700 PRINTP$<3).; TAB< 1 1 ) : INPUT"FIX TIME " .• FT $

710 PRINTP*(4);TAB<8> •• INPUT"DRAIN TIMES ",DR*

720 PRINTP$<6>; "PRESS 0 TO START TIMING" : PRINT
730 PR I NT "PRESS - TO CHANGE TIMINGS" ; PRINT
740 PRINT "PRESS = TO START OVER"

750 GET A$ •- 1 FR$= " " THENGOTO 750
760 I FAS="0" THENGOTO 790
770 I FA$= " - " THENGOT 0 660
780 GOTO 140

790 REM###### DEVELOPING ROUTINE

800 PR I NT '73 "

810 PRINT" S) PROCESS CONTROL "

820 PRINTP$< 1 ) ; TRB<4) ; "DEVELOPING TIME " PRINTP#<2> ; TAB<9> J "DRAIN TIME "
830 PRINTP*<3) ; TAB<6) ; "ST0PBATH TIME " PRINTP$<4>;TRB<9); "DRAIN TIME "
840 PRINTF*$<5), TAB< 11); "FIX TIME "

850 TM*=DT* P=1 = T=20 ■' T I $="000000"

860 GOSUB 1100

870 P0KE5947 1 , 4 F0RX= 1 TO 1 000 • NEXT
880 POKE59471.0

890 TM$=DR$ ■ P=2 T=20 T I $="000000"

900 GOSUB 1100

9 1 0 P0KE5947 1,4 F0RX= 1 TO 1 000 NEXT
920 PGKE59471 ,0

930 TM#=ST $ : P=3 : T=20 = T I $= " 00000O "

940 GOSUB 1100

950 PGKE594 71,4: F0RX= 1 TO 1 000 : NEXT
960 P0KE59471 , 0

970 TM*=DR* : P=4 •' T=20 : T I * = " 000000 "

980 GOSUB 1100

990 P0KE59471 , 4 • F0RX=1 TO 1000 NEXT
1000 POKE59471,0

1010 TM*=FT* = P=5 T =20 ; T I $= " 000000 "

1020 GOSUB 1100

1 030 P0KE5947 1,4 F0RX= 1 TO 1 000 •' NEXT
1040 P0KE59471 , 0

1050 PRINT : PRINT : PRINT : PRINT"PRESS 0 TO REPEAT" • PRINT
1060 PR I NT "PRESS * TO START OVER"

1 070 GETAS : I FA$= " " THEN 1 070
1080 I F A$= " 0 " THENGOTO 790
1090 GOTO 140

1100 REM##*### CLOCK/TIMER ROUTINE
1110 MIN*=LEFT*<TM*, 1) SEC*=RIGHT*aM*,2>

1120 PRINTP#<P> , TAB(T) ; "H "

1130 PRINTP*<P>;TABa>; "BJ " j MID$(TI^ , 3, 2> ; " : ";RIGHT$<TI$,2); " "

1140 GETRS •• I Ffi$= " " THENGOTO 1 1 60
1150 GOSUB 1230

1160 IFRIGHT*<TI*,2>=SEC$THENG0T0 1180
1170 GOTO 1130

1180 IFRIGHT$<NID$ai$,3,2>,l>=MIN$THENG0TG 1200

1190 GOTO 1130

1200 PRINTP$<P>;TAB<T >; "1

1210 PRINTP*<P>;TAB<T>; " ";MID*<TI*,3,2>; " : ";RIGHT#<TI#,2>; " "

1220 RETURN

1 230 H*=T I $ I FA$= " " THENF'R I NTP# < P ) ; TAB < 28 > ; " HOLD " : GOTO 1 250
1240 GOTO 140

1250 GET A$ • I FA$= " " THENGOT 0 1250

1260 IFA$=" "THENPRINTP$(P>;TAB<28>; " " ; T I $=H$ ; RETURN

1270 GOTO 660
1280 END

Fig. 1. Darkroom Master circuit diagram.

Microcomputing January 1980 127

PRESS . FOR EXPOSURE CONTROL
PRESS - FOR PROCESS CONTROL

PRESS . TO FOCUS

PRESS - TO SET EXPOSURE TIME

PRESS « TO START OVER

Photo 1.

Photo 2.

PRESS - TO SET EXPOSURE TIME
PRESS = TO START OVER

EXPOSURE

TIME? 010

PRESS

0

TO

START/REPEAT EXPOSURE

PRESS

•

TO

CHANGE EXPOSURE

PRESS

-

TO

FOCUS

PRESS

2

TO

START OVER

Photo 3.

Photo 4.

EXPOSURE

TIM “

PRESS

0

TO

START/REPEAT EXPOSURE

PRESS

•

TO

CHANGE EXPOSURE

PRESS

-

TO

FOCUS

PRESS

2

TO

START OVER

DEVELOP TIME ? 130
STOPBATH TIME ? 015
FIX TIME ? 200
DRAIN TIMES ? 05

PRESS 0 TO START TIMING
PRESS - TO CHANGE TIMINGS
PRESS » TO START OVER

Photo 5.

result. It prints the clock at the
correct place on the screen in re-
verse video while the clock is
running, and then in normal
video after the clock has
stopped, going on to the next
timing function. This allows you
to see at a glance where you are
in the timing sequence.

The Hardware

The hardware to make it work
is shown schematically in Fig. 1.
The upper half of the circuit is
the beeper for the time-out indi-
cator of the processing section.
The PET user port, pin E, is con-
nected through two buffers to

an optoisolator. The opto-
isolator’s output is sent through
two more buffers that gate the
power to a 555 astable oscillator.

When the computer executes
a POKE 59471,4, a high-level
signal is present on pin E. This
activates the optoisolator and
the following buffers, which turn
on the power to the oscillator,
generating a tone. POKE
59471,0 turns off the tone.

The rest of the circuit is simi-
lar, but a relay is powered by the
buffers instead. The relay con-
tacts are connected to ac power
sockets for control of the enlarg-
er and safelight. The optoisola-

Photo 6.

tors are there to protect the PET
from the potentially dangerous
110 volts ac. Don’t leave them
out. This is one place where you
can’t skimp.

To carry this further, U1 and
the optoisolators are powered
by the PET through connections
on the PET cassette port— pin A
for the ground and pin B for +5
volts. The remainder of the cir-
cuit (U2, the 555 and the relay)
are powered by a user-supplied
5 V supply. Any method of con-
struction can be used as long as
the 110 V connections are hefty
enough to carry 100 Watts with
no problem. Use twisted pairs

to carry the signals from the PET
to your enlarger/safelight con-
trol box.

Making It Work

When the hardware is con-
structed and connected, plug
the enlarger and safelight into
the appropriate outlets and load
the program. As you probably
know, you must use a safelight
in the darkroom, that is, a lamp
with a special filter that emits
light that your photo materials
are not sensitive to. This en-
ables you to see what you are
doing without ruining the light-
sensitive materials.

But where do you find an af-
fordable 5V2 x 7Vi inch safe-
light filter for your PET? Go to
your local graphic arts or print-
er’s supply shop and purchase a
sheet of Amberlith or Rubylith.
These are materials manufac-
tured by Ulano, Inc., that allow
your printer to mask off portions
of the artwork he is photograph-
ing to prevent the camera from
“seeing” them. They work by
blocking the light waves that the
film is sensitive to and passing
the ones the film is insensitive
to.

We can put this to work in our
darkroom by covering the PET
screen with Rubylith if we are
using orthochromatic materials
(such as litho film) and by using
Amberlith if we are using pan-
chromatic materials such as en-
larging papers. These products
come in sheets and rolls and are
intended to be stripped from the
clear backing sheet for use;
however, just cut out a section
large enough to cover the PET
screen and hold it in place with
masking tape along the edges.

To keep light from leaking
out, turn the brightness all the
way down and keep the PET at
least four feet away from any
light-sensitive materials. You
may have to use a double thick-
ness of Rubylith or Amberlith.
Of course, you cannot use any
safelight with panchromatic
sheet film or with color
materials, as they are sensitive
to almost all visible light wave-
lengths. So set up your expo-
sure and then cover the PET
with a dark cloth before bringing
out those materials.

To expose a print, enter ex-

128 Microcomputing January 1980

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posure control by pressing the
decimal key (Photo 1). You can
now focus by again pressing the
decimal key (Photo 2). When you
have focused, press the minus-
sign key (Photo 3). Type in the
exposure time (Photo 4). If it is
less than one minute, type a
leading zero. For example, for a
five-second exposure, type in
“05”; for a ten-second exposure,
type in “010.”

For an exposure of one min-
ute or more, type in the number
without a leading zero and with-
out a colon. The computer adds
the colon for you, i.e., type in
“130” for one minute and thirty
seconds. You must press return
when entering your times for ex-
posure and processing; all other
entries are under GET command
control and do not require a
return.

You now have another menu
to choose from. You can start
the exposure, change your expo-
sure, recheck your focus or es-
cape back to control.

Start your exposure (Photo 5).
The running clock will show in
reverse video, properly for-
matted, at the point on the
screen where you entered the
exposure time. Remember that I
promised you I would explain
about the space bar? Here’s
where it comes into use.

Suppose the print you are
making needs a certain area
“burned in,” that is, given more
exposure than the rest of the
print. Just press the space bar
and the word “hold” will appear
next to the clock. This halts the
timing, freezes the clock and
leaves the enlarger on, allowing
you to burn in the chosen area.
When you are finished burning
in, press the space bar again.
The “hold” will disappear and
the clock will pick up from where
it left off.

When the clock has finished
its count, it reverts to normal
video, the enlarger turns off and
the safelight turns on. Your
menu is still on the screen for
choosing the next function. To
process the print, press the
“equal” sign to get back to con-
trol and the “minus” sign to go
to process control.

To process the print (Photo 6),
enter the times for developing,
stop bath, fixing and drain. A

DEVELOPING

TIME ■■

aa hold

DRAIN

TIME

STOPBATH

TIME

DRAIN

TIME

FIX

TIME

DEVELOPING TIME 01:30
DRAIN TIME 00:05
STOPBATH TIME 00:15
DRAIN TIME 00:05
FIX TIME 02:00

PRESS 0 TO REPEAT
PRESS * TO START OVER

Photo 7.

timer is not included for wash-
ing the print because it would tie
up the computer for as much as
two hours, and washing a print
does not require to-the-second
accuracy. You can use a wall
clock or your wristwatch to time
the wash step (don’t use an LCD
wristwatch with a tritium back-
light; it will fog most photo ma-
terials).

When entering times, the
leading zero rule applies. If you
do not wish a drain time be-
tween steps, just enter “00”
when asked for that time.

As with the exposure control,
the clock appears in reverse
video (Photo 7), formatted, and
reverts to normal video at the
end of the count. You can use
the hold control here also, as
you may want to use hot devel-
oper or ferricyanide bleach on
the print.

And in both exposure and pro-
cess controls, you can repeat
the timing sequence without re-
setting the clock (Photo 8). This
is helpful if you have to batch-
process some prints, such as
the 100 prints from one negative
I mentioned earlier. You could
first expose and then process all
of them.

Modifications

If you are more into color
prints than black and white, it’s
just as easy to control the pro-
cess. You will have to change
the process step labels, lines
680-840. And while you are in
there, add the POKE commands
to turn your motorized agitator
on and off with the processing
steps! The same principles ap-

ply with any process (such as
films or litho materials); you may
have to add or delete some
steps and change the labels.

And to make the work easier,
add an external numeric keypad
for remote entry of exposure
and processing times while the
PET is safely away from the en-
larger and the sink. Get any 16
button keypad with SPST
switches and wire it as shown in
Table 1. 1 have not tried to make
a keypad remote yet, but accord-
ing to what I have read this
should work well.

To make the program even
more useful, add routines to
keep track of the number of
prints processed in a gallon of
developer, for converting expo-
sure times when using variable-
contrast filters and to add an
A/D converter for a densitometer
to let your computer calculate

Photo 8.

the exposure times.

Conclusion

There are a lot of things you
can do with the hardware and
the program when not running
Darkroom Master. You can
switch two ac devices and use
the clock routine in real-time
control applications. I’ll soon be
moving to a new house and look
forward to putting my computer
to work in a practical applica-
tion. The program as written
runs in 3.8K of PET memory.

I’ll be happy to answer any
questions you may have or to
hear about how you have used
Darkroom Master; just be sure
to include return postage if you
want a reply.

I want to thank my wife, Millie,
for typing the manuscript, and
Emory Wright for the use of his
PET printer. ■

From Pet

To One Side

The Other Side

Keyboard

Of Switch

Of The Switch

ConnectorPin

On Keypad

To The Pet Key-
Board Connector
Pin

G

DECIMAL POINT

10

G

0

9

G

1

7

G

2

8

H

3

7

G

4

5

G

5

6

H

6

5

G

7

3

G

8

4

H

9

3

H

9

3

H

MINUS

9

H

EQUALS

10

C

SPACE

9

F

ENTER

5

Table 1.

130 Microcomputing January 1980

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* 'Everyone who builds kits or
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needs an extender board and logic probe .
This is a fine combination . I only wish I
had mine two years ago.

Robert L. Leffert
Kilobaud Microcomputing
August 1979

J

S-100 CONTROL BOARD a simple to use interface board

for all S-1 00 buss computers. Let your computer listen to the

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Order direct or contact your local computer store. >

iS Reader Service— see page 227

Microcomputing January 1980 131

RECYCLED)
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132 Microcomputing January 1980

The LIBRARY 100 from TBS is without doubt the greatest software
bargain ever. Released in November 1978, it has sold thousands in
44 countries. Written for the TRS-80, LIBRARY 100 contains 100
programs on five tapes. Most of the programs can be run on a 4K,
Level II computer. Designed to be a basic computer library, it provides
a series of programs over a broad range of topics. All programs but
one are written in BASIC and can easily be modified to suit your
own purposes.

“The program mix is eclectric, interesting, and curious ... If I had a
Level II TRS-80 and one or more grade-school children, or if I were a
hardcore software collector, or if I had little software and wanted to
get a lot of it with a minimum of bother, I’d buy the Library 100.”
Stephen Gray, Creative Computing, April, 1979.

“. . . a basic computer library for the hobbyist, parent or business-
man.” Kilobaud Microcomputing December 1978.

The programs are spread over five general categories; Finance,
Education, Graphics, Home and Games. As an added bonus, the
LIBRARY 100 contains Tiny PILOT, a condensed version of the high
level language primarily used in education. It is perfect for teachers,
parents, students and sales trainees. Using only six commands, even
a child could be programming in minutes. The other programs are
as follows:

FINANCE: Present Value of Future Sum, Simple Interest for Days,
Future Value of Present Sum, Amortization Schedule, Interest Rate-
Compound Interest, Interest Rate-Installment Loan, Days Between
Dates, Term of Installment Loan, Present Value of Series of Payments,
Real Estate Investment Analysis, Nominal-Effective Interest, Internal
Rate of Return, Future Value, of Regular Deposits, Regular Deposits
for Future Value, Depreciation (Amount, Rate, Salvage Value,
Schedule), Bond Present Value, Bond Yield to Maturity, Sale-
Cost-Margin-Day of Week, Moving ad.

EDUCATION: Multiplication & Division, Addition, Subtraction,
Fraction & Decimal, States & Capitals, States and Order of Entry,
States and Date of Entry, States and Abbreviations, Inventors and
Inventions, World Capitals & Countries, Urban Areas and Population,
Authors & Books, Presidents and Order, States and Largest City,

Base Numbers.

GRAPHICS: Front Cover, Wierd, Rat Race, Random Ad, Fireside,
Left-Right Ad, Blocks, Herring, Launch, Blinker, Snoopy, Snow, Step
Ad, Step Ad Two, Graphic Words, War Games.

HOME: Bartender, Nutrition, Conversion, Perpetual Calendar, Base
Conversion, Calculator, Vacation Check-off List, Telecode, Message
Board, Night Check-off List, Expense Account, Babysitter, Drunk-
ometer, Remember, Christmas List, Mileage.

GAMES: Jumble, Search, Memory Quiz Letters, Sting Ray, Russian
Roulette, Wheel of Fortune, Towers, Decision, Memory Quiz Numbers,
Doomsday, Star Trek,™ Sketch, Flipper, Life, Fifteen, Speedy, Count,
Road Race, Stars, Odd One, Spy Ship, Horse Race, Scissors, Craps,
Star Blazer, Tiger Shark, Unjumble, Mind Reader, Roach Race,

Jumble 2, Gypsy.

The price for the LIBRARY 100 is only $49.50. That’s less than
$.50 per program. Join the thousands of users who are already enjoy-
ing this exceptional software package. Only from TBS. (We are
currently working on a Library for the APPLE.)

TBS has other great software for your TRS-80. CHECKBOOK II,
INFO SYSTEM, & EXERCISER are general applications. BASIC
TOOLKIT, SYSTEM DOCTOR & TERMINAL CONTROL are systems
utilities. BUSINESS MAIL LIST, DATA MANAGER, CHECK
REGISTER ACCOUNTING SYSTEM & ANALYSIS PAD are strong
applications for business. TBS also has DISK HEAD CLEANERS
for TRS-80 and APPLE and GRAN MASTER DISKETTES, the
best on the market.

TBS is YOUR COMPANY, and to you we pledge to produce
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please contact us at the numbers below.

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THE BOTTOM SHELF, INC.

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iS Reader Service— see page 227

Microcomputing January 1980 133

TRS-80 Printer Interfaces:
Serial and Parallel Designs

Save $200 or more by constructing your own interface circuits.

Rod Hallen
Road Runner Ranch
PO Box 73

Tombstone AZ 85638

T he TRS-80 is a great per-
sonal computer. I don’t
think that it can be beat in its
price class. I’ve had mine for
several months and I really en-
joy using it. It is a simple
machine, yet it is capable of
quite sophisticated results.

I have owned one or more
microcomputers for more than
two years. I use them for pro-
gram development and for
manuscript preparation and
printing. Since both of these
tasks require hard-copy facil-
ities, the first thing I did, after
buying my TRS-80, was to deter-
mine the easiest (and cheapest)
way to interface a printer.

You might ask, “Is a printer
really necessary to write pro-
grams?” Yes, because it is very
difficult to get a good idea of the

flow of your program without be-
ing able to see it all in one piece.
It is also easier to find errors and
make corrections. The screen is
just not large enough to hold all
of the information required.

The designers of the TRS-80
obviously understood the need
for hard-copy capability since
Level II BASIC contains the
statements LPRINT and LUST,
both of which output to the
printer port instead of to the
screen. The Expansion Interface
includes a parallel port to feed a

13

-^>v

|IC3cVg_
jol 7400 P~

~1

Ijj—

1

TO

+ 5 1

|IC3A ^

\y'

IC3B \

TRS-80

0ND

17400

~2l >

1 s| 7400 J

IC6

74123

i

12

23

IC5

74100

3

2

6

IC4

74125

5

8

9

It

12

TO

„ LINE
PRINTER
OR UART

printer.

However, therein lies a dilem-
ma. In order to implement hard
copy on the TRS-80 as envi-
sioned by Radio Shack, it is
necessary to purchase the Ex-
pansion Interface and a line
printer. This is an outlay of from
1300 to 1600 dollars, depending
where you buy the printer. What
about those of us who already
have a printer?

I have been using the Teletype
Model 43 KSR for almost a year,
and I like it. It prints either 10 or
30 cps, is very quiet, has an
RS-232 serial interface and has
been 100 percent reliable. In ad-
dition, it prints lowercase; the
Centronics 779 printer does not.
This is a definite plus! Why
couldn’t I use it for hard copy in-
stead of the parallel line printer
that Radio Shack intended?

The Expansion Interface also
provides facilities for disk
drives, more memory and a sec-
ond cassette recorder. I don’t
plan to add any of these to my
unit, so I decided to design an in-
terface to fit directly between
the expansion port on the back
of the TRS-80 keyboard unit and
the Model 43.

1C

+ 5

GNO

7400

14

7

7404

14

7

7430

14

7

74100

24

7

74123

16

8

74125

14

7

Fig. 1. Schematic drawing of the parallel interface for the TRS-80 expansion port. This will drive a Centronics 779 or similar line printer
directly. Many 1C substitutions are possible. IC6couldbea 74121, IC3a 7402; IC5 could be replaced with two 74175s, and the 74125 with
an 8T97 or 74367. Most of these changes would require some circuit changes.

134 Microcomputing January 1980

The complete TRS-80 to RS-232 interface. The card on the left is
the address decoder and parallel port. On the right is the Elec-
tronic Systems UART and Baud Rate Generator board with their
TTL to RS-232 converter mounted on top of it. Shown to the rear is
the interconnection assembly. The connector on the left plugs into
the expansion bus on the back of the TRS-80 keyboard unit, and
the two interface cards plug into the connectors on the right. The
transmit and ground leads to the printer connect to two pins on the
top right-hand connector.

My design was successful, as
you will see, and the total cost
for a serial RS-232 interface was
less than $50. If you would like
to plug a parallel line printer,
such as the Centronics 779,
directly into the keyboard ex-
pansion port, I’ll show you how
to do that for less than $5!

The Interface

First let’s look at some of the
requirements that our interface
must meet. I was unable to ob-
tain any information from Radio
Shack on this subject, so what
follows was learned by my
studying the Level II print driver
routine and the Expansion In-
terface schematic.

The printer port is addressed
as a memory location instead of
as an I/O port. This is called
“memory-mapped I/O.” The
memory location used is 37E8
hex (14312 decimal), which is
configured as both an input and
an output port.

The print driver routine first
reads the input port to see if the
printer is ready to receive the
next character. If it is, the char-
acter is sent to the output port,
and then input port status is
read continually until the printer
is ready for the next character.
We can’t just dump text to the
printer at microprocessor speed
because the printer is not able
to handle characters that fast.

While it is reading the printer
input port the processor is also
checking to see that the printer
is not out of paper or hasn’t
some other fault. If you attempt
to LPRINT or LUST to the printer
when it has a problem or is out
of paper, nothing will happen. In
this case it is up to you to deter-
mine what the fault is.

In order to implement a print-
er interface that will work with
the TRS-80, you must satisfy the
following requirements:

1. Decode memory address
37E8 hex.

2. Determine whether the pro-
cessor desires to read or to
write.

3. Gate status information onto
the data bus for a READ.

4. Latch ASCII character from
data bus for a WRITE.

5. Provide a WRITE strobe to
UART (serial) or printer (parallel).

Fig. 1 shows the basic inter-
face. This will drive a parallel
printer, such as the Centronics
779, directly, and it should cost
less than $5, not including the
cost of the two connectors re-
quired, to build. It can also be
used to drive a UART if you in-
tend to use a printer that has a
serial RS-232 interface. I’ll get to
that in a moment.

First let’s look at Fig. 1 and
see how it satisfies the interface
requirements listed above. ICs 1
and 2 are SN7430 8-input NAND
gates. They are used to decode
the desired address— in this
case, 37E8H. I won’t go into the
conversion of numbers from hex
format to binary format, so
you’ll have to take my word
that 37E8H is equal to
001101 1 1 11101000B. From left
to right, as shown in Table 1,
these 16 binary digits equate to
the microprocessor address
lines A15 to AO.

Since some of the address
lines will be high and some will
be low when the desired ad-
dress (37E8H) appears on the
address bus, we use inverters to
give each line the correct sense.
This means inverting A15, A14,
All, A4, A2, A1 and AO. Note
that these correspond to the
zeros in Table 1. When all 16 in-
puts to the 7430s are high
(binary 1), the output of IC3b at
pin 6 (address decode) will go
high. This happens when, and
only when, the address 37E8H is
on the address bus.

We can determine whether
the processor wants to read or
write by monitoring the RD and
WR leads from the keyboard ex-
pansion port. These are active
low signals. This means that the
processor will take RD low when
it wants to read and WR low
when it wants to write.

By NANDing “address de-
code” from IC3b, pin 6, with
RD we can generate a “READ
strobe” at pin 1 1 of IC3d. NAND-

ing “address decode” with WR
will give us a “WRITE strobe” at
pin 8 of IC3c. These two strobes
correspond to the 37E8 READ
and 37E8 WRITE leads found on
the TRS-80 Expansion Interface
schematic.

When 37E8 READ goes active
(low), the Tri-state buffer (IC4)
will gate status information on-
to the data bus for the processor
to read. This includes: “printer
busy,” “out of paper,” “unit
select” and “fault.” The first two
are active low and the last two
are active high.

When 37E8 WRITE goes ac-
tive (low), the octal latch (IC5)
latches (stores) the ASCII
character that the processor
has put on the data bus. This is
necessary because the charac-
ter will only be on the data bus
for a few microseconds or

so— not long enough for the
printer to utilize it. The latch will
hold this character until the next
one is sent.

Finally, the one shot (IC6) will
provide a strobe to the printer
telling it that the next character
is ready to be printed. IC6
lengthens the 37E8 WRITE
pulse, and it isn’t necessary if
you are going to use a UART.
Then the output of IC3c, pin 8
can go directly to the UART.

At this point, if you are going
to use the Centronics 779 or an
equivalent line printer, you can
jump down to the section on
construction. However, if you
are going the RS-232 route as I
did, read on.

Serial RS-232

A serial port handles data
(8-bit ASCII characters) one bit

Address bus -> A15 A14 A13 A12 All A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
37E8 hex ~> 001101111110100 0

Table 1. The relationship between the address bus and a binary 16-bit address. Since the
NAND gates (ICs 1 and 2) of Fig. 1 require a high level (binary 1), address lines that are low
(binary 0) are inverted before being used.

Microcomputing January 1980 135

c

:

TO

PARALLEL
PRINTER
► (FIG. 3)

OR TO
UART
( FIG. 4)

Fig. 2a. The interconnection wiring between the TRS-80 expan -
sion port and the parallel interface of Fig. 1. The leads on the right
side go to the parallel printer of Fig. 3 or to the UART of Fig. 4a.

at a time as opposed to a par-
allel port, which passes all eight
bits at once. Loosely defined,
the RS-232 standard says that a
high (or binary 1) should be + 12
volts and that a low (or binary 0)
should be - 12 volts. Up to this
point our signals have all been
TTL levels in which a high is
represented by +5 volts and a
low by ground.

In order to implement a serial
RS-232 port we must take the
eight bits presented to us on the
data bus in parallel and send
them to the printer one bit at a
time. This includes providing the
proper timing for the particular
printer involved. We must also
change the TTL levels of +5
volts (binary 1) and 0 volts
(binary 0) to the RS-232 levels of
+ 12 volts and -12 volts.

The first two parts of this task
are easily taken care of by an 1C
called a universal asynchronous
receiver/transmitter, or UART.
There are many different ver-
sions of the UART available
from the 1C manufacturers; the
one I used was the AY-5-1 01 3A.
The UART is a full-duplex device
and, as its name implies, it will
receive as well as transmit. In
this application we will only be
using the transmitter.

Construction

You can build the circuit of
Fig. 1 in any way that is conve-
nient. Perfboard or Vectorbord
can be used, but I prefer to build

all of my circuits on standard
44-contact prototype boards.
The Hobby Board from OK Ma-
chine and Tool is the one I use.

The + 5 volts required by Fig.
1 are available from the key-
board expansion port, but I don’t
know how much current this will
supply. If the fuse blows or the
power supply gets too hot, then
you will have to provide a
separate source of + 5 volts. Us-
ing the “LS” versions of the 7400
series ICs involved will cut down
on the current requirements.

Fig. 2a shows the intercon-
nections between the TRS-80
keyboard expansion port and
the parallel interface (Fig. 1).
Fig. 2b is an explanatory draw-
ing of the manner in which the
contacts on the expansion port
are counted. Fig. 3 contains the
connections between the par-
allel interface and the Cen-
tronics 779 or similar line
printer.

Two connectors will be re-
quired. The one that plugs into
the keyboard expansion port is
identified in my TRS-80 manual
as AMP part number 88103-1.
Unfortunately, my local Radio
Shack store does not stock
them. Two different versions are
available from Applied Inven-
tion, RD2, RT21, Hillsdale NY
12529. One is the solder-tail
type; the other comes with 18
inches of ribbon cable attached.

You will also need a connec-
tor to match the one on your

13 15 17 19 21 23 25 27 29 31 33 35 37 39

l 1 l 1 l 1 I > I 1 I 1 I 1 I 1 I 1 I 1 I 1 I 1 I 1 1 L

TZZT

4

xzr

6

i ii ii ii ii ii ii i i > i i i — i i — i i — i L_u i — i i — r L_zr

10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

TRS-80 EXPANSION PORT REAR VIEW

Fig. 2b. Rear view of the TRS-80 expansion port from the keyboard
unit.

printer. This will depend on the
type of printer.

For those of you who want to
use a printer with an RS-232 in-
terface, such as the Teletype
Models 33 or 43, the circuitry be-
comes a little more compli-
cated, but it is still well worth
the trouble if it saves you the
cost of a new printer.

Rather than build my own
UART board I chose to use the
UART and Baud Rate Generator
board available from Electronic
Systems, PO Box 21638, San
Jose CA 95151, (408) 226-4064.
Write or call for a copy of their
catalog, which contains many
useful computer-related circuit
kits and etched boards.

You will find this UART board
described in my article “Parallel
Port to RS-232,” Kilobaud
Microcomputing , April 1979,
p. 62. You can save quite a bit of
money by purchasing the bare
board if you already have a
UART on hand.

I chose to combine the UART
board, which is constructed on a
44-contact card, with a TTL to
RS-232 converter kit also avail-
able from Electronic Systems.
This mating and the modifica-
tions required are described in
the above article. I advise any-
one who is going to tackle this
project to read it. The parallel-to-
serial and TTL-to-RS-232 conver-

N0T£ • STRAP THE FOLLOWING CONTACTS ON

THE PRINTER PLUG TO EACH OTHER AND
TO GND ; 2,4,6,8,10,12,14,16.18,20.22.24.
27,31,33,34.

Fig. 3. Connections to the Cen-
tronics 779 or similar line
printer. The pin numbers shown
are for the plug that mates to
the connector on the back of
the printer.

sion circuits can be built from
scratch, but it is much easier
and quicker when you have ac-
cess to a PC board with the cir-
cuit already etched on it.

Fig. 4a shows the intercon-
nections between the parallel in-
terface, the UART board and the
printer serial port. In this case,
Fig. 4b should be added to Fig.
2a to make the interface believe
that it is connected to the 779
printer. Put this on the same
board that Fig. 1 is built on.

Note that in addition to +5
volts, we are also calling for
+ 12 volt and - 12 volt supplies.
This is to power the UART and to
provide the RS-232 levels. Do not

TO

PARALLEL
INTERFACE
{ FIG. 2A)

r STROBE

P

00

Y

Dl

X

02

W

ELECTRONIC

QVCTCMC

D3

V

J 1 j 1 LMg

BAUD RATE

J 04

u

GENERATOR

AMn 1 1 A DT

05

T

AINU UAn 1

BOARD

06

s

WITH

07

R

TTL TO
RS-232

BUSY

17

CONVERTER

GNO 1

’1

RS-232

PRINTER

BAUD RATE a
CLOCK INPUTS
X-CONN AS
REQUIRED

Fig. 4a. Connections in and out of the combined UART, baud rate
generator and TTL-to-RS-232 converter. See the reference in the
text for more information on this combination. The desired baud
rate should be connected to the transmit clock (T-CLK). The strap
shown between 4 and 5 on the RS-232 printer plug is to satisfy an
internal requirement.

136 Microcomputing January 1980

Switch

Purpose

Condition

SI

Input strobe polarity

ON = NEG OFF = POS

S2

Output strobe polarity

ON = POS OFF = NEG

S3

Parity

ON = ODD OFF = EVEN

S4&S5

Bits per Character

S4 S5 BITS

ON ON 5

OFF ON 6

ON OFF 7

OFF OFF 8

S6

Stop bits

ON = 1 OFF = 2

S7

Parity

ON = YES OFF = NO

Table 2. Options available on the Electronic Systems Baud

Rate Generator and UART board. These are actually features of
the A Y-5-1013A and similar UARTs.

take the +5 from the keyboard
to power Fig. 4a. Current re-
quirements are low, and a sim-
ple supply will suffice. It must,
of course, be regulated.

As mentioned, I built Fig. 1 on
a 44-contact Hobby Board; the
UART circuitry is constructed
on a similar board. Then I
mounted two 44-contact edge
connectors above each other on
a chassis with corner brackets
as shown in Fig. 5. These con-
nectors are readily available and
come in solder-tail and wire-
wrap types. I prefer the wire-
wrap type since I am continually
changing things.

The cables to the TRS-80 and
the printer exit to the rear. Since
there is no need to get at the
cards once everything is work-
ing OK, a cover could be built to
improve the appearance of the
unit. If a large enough chassis
were used, the power supply
could be built inside of it.

I’m using a minicomputer
power supply that I picked up at
an electronics surplus store.
They also had some surplus
card cages for the 44-contact
connectors that would have
made an ideal mounting as-
sembly. I’m sorry that I didn’t
pick them up, but I’ll be watch-
ing for some for my next project.

After everything is wired
together the options must be
determined. Note in Fig. 4a the
contacts identified as baud rate
and clocks. The baud rate re-
quired for your printer must be
connected to the Transmit
Clock. My Model 43 operates at
300 baud; therefore, contact 11
(300 baud) is connected to con-
tact 15 (Transmit Clock). See
Fig. 4c for a bottom view of the
44-contact edge connector that
the Baud Rate Generator and
UART board is plugged into. The

EACH

r FAULT '•» I/4W

OUT PAPER

l ' l

Fig. 4b. This little mod is used
with Fig. 1 when it is connected
to a UART. This will properly
condition fault lines that nor-
mally go to the line printer.

baud rate clocks should be ad-
justed to the correct frequency
as explained in the above re-
ferenced article.

There is also a multiple DIP
(double in-line package) switch
on the UART board that must be
set. Table 2 gives the options
available. My requirements
were: SI— ON (input strobe
negative), S2— not used, S3
—OFF (even parity), S4— ON
and S5— OFF (seven bits per
character), S6— OFF (two stop
bits) and S7— ON (parity). The
only settings that you might
have to change relate to parity.
If in doubt, leave S7 off and ig-
nore S3.

Implementation

With the parallel interface in-
stalled between the keyboard
and a Centronics 779 or equiv-
alent, all that is required for hard
copy is to substitute LPRINT
and LUST statements for PRINT
and LIST as necessary. Unfor-
tunately, at the last minute a
snag that apparently was going
to scuttle my intention to use
the Model 43 appeared.

For some reason the writers
of Level II BASIC apparently
decided not to output a line feed
after each carriage return. A line
feed is not required with print-
ers, such as the Selectric, that
automatically provide one each
time a carriage return is re-
ceived. I don’t have access to a
Centronics 779, but I have to

BOTTOM VIEW

44 CONTACT

EDGE CONNECTOR

A I

B 2

C 3

D 4

E 5

F 6

H 7

J 8

K 9

L 10

M ||

N 12

P 13

R 14

S 15

T 16

U 17

V 18

W 19

X 20

Y 21

Z 22

Fig. 4c. A bottom view of the
UART and baud rate generator
connector showing how the
contacts are identified. You
can assign your own contacts
on the interface board.

assume that it incorporates that
feature. However, neither the
Model 33 nor 43 does, and it is
awfully hard to read a program
listing that is all printed on one
line.

I thought I was done for until a
little study revealed that the ad-
dress of the print driver routine
is stored in RAM and not in
ROM. All that should be required
is to poke an address into this
storage location pointing to a
new print driver residing in high
memory. This may sound like ex-
tra work since the print driver
routine would have to be loaded
every time the TRS-80 was
turned on, but it still beats buy-
ing another printer.

There are many different
ways of loading the new print
driver routine. If you are running
T-BUG, you can create a “SYS-
TEM” program on tape and load
it each time you use the TRS-80.

1 - 1 / 2 *

Fig. 5. One way of mounting
the two circuit boards de-
scribed in this article. Many
other arrangements could be
worked out. However you do it,
keep the leads from the TRS-80
to the interface and from the
interface to the printer as short
as possible.

There are also other assembly-
language monitors available,
such as the ESP-1 from Small
System Software.

I’ve written an assembly-
language monitor in Level II
BASIC that is described in
“Monitor,” Kilobaud Micro-
computing, June, 1979, p. 26.
You can also write a straight
BASIC program to poke the
necessary information into
memory.

Program A is the listing of the
new print driver routine that I
have been referring to. It will
pass each character to the print-
er port whenever it is called, and
it will add a line feed (0AH) each
time that it detects a carriage
return (ODH).

The print driver starting ad-
dress is stored at locations
4026H and 4027H. These loca-
tions normally contain 058DH,
the address of the Level II print
driver in ROM. 4026H and 4027H
must be changed to point to the
address of the new print driver,
7FE0H.

Program B does the same
thing that Program A does, ex-
cept that an assembly-language
monitor is not needed. Each
time Program B is run it will
change 4026H and 4027H and
load the print driver into memory
starting at 7FE0H.

Now let’s look at the software
steps necessary to make
everything operational. When
you turn the TRS-80 on it asks
you, “MEMORY SIZE?” You type
32734 to reserve some high
memory for the new print driver.

If you are not going to use an
assembly-language monitor,
you can skip this paragraph.
Load your monitor, enter Pro-
gram A at 7FE0H, EOH at 4026H,

Microcomputing January 1980 137

ADDRESS

MACHINE

LABEL

MNEMONICS

COMMENTS

CODE

7FE0

3A E8 37

LOOP

LDA PORT

READ STATUS

7FE3

E6 F0

ANI F0H

MASK LOUER HALF

7FE5

FE 30

CPI 30H

IS PRINTER READY?

7FE7

C2 E0 7F

JNZ LOOP

IF NOT, TRY AGAIN

7FEA

79

MOV A , C

GET CHARACTER

7FEB

FE 0D

CPI CR

IS IT CARRIAGE RETURN?

7FED

C2 F8 7F

JNZ OUT

IF NOT, GOTO OUT

7FF0

32 E8 37

STA PORT

URITE CHARACTER

7FF3

0E 0A

MVIC LF

LOAD LINEFEED

7FF5

C3 E0 7F

JMP LOOP

CHECK STATUS

7FF8

32 E8 37

OUT

STA PORT

URITE CHARACTER

7FFB

C9

RET

RETURN TO BASIC

Program A. The print driver routine that is required if your
printer does not insert a line feed after each carriage return it
receives. This was written on an 8080 assembler, but the TRS-80
doesn 7 know any better and will run it anyhow. Although this is
for the Level II 16K TRS-80, it will work in the 4K machine by
changing all of the 7Fs to 4F. Your response to MEMORY SIZE?
would then be 20447.

10 REM ♦PRINT DRIVER ROUTINE*

20 REM *BY ROD HALLEN TOMBSTONE, AZ*

30 REM *16 JANUARY 197?*

40 POKE 16422,224
50 POKE 16423,127
60 FOR 1=1 TO 28
70 READ D
80 POKE 32735+1, D
90 NEXT I

100 DATA 58,232,55,230,240,254,48
110 DATA 194,224,127,121,254,13,194
120 DATA 248,127,50,232,55,14,10
130 DATA 195,224,127,50,232,55,201
140 END

Program B. This is Program A rewritten in Level II BASIC. Run-
ning it will POKE the start address of the new print driver rou-
tine at 4026H and 4027H. Note that the address is stored least
significant byte first, i.e., EOH in 4026H. It will then POKE the
new print driver starting at 7FE0H. Write this one for 4K by
changing 127 to 79 each time it appears in the data statements.

7FH at 4027H, and make a tape
for later use.

Program B can be loaded
from the keyboard like any other
BASIC program, and a “CSAVE”
will give you a tape copy.

From now on, all you have to
do is load the print driver from
tape. If it is the Program. B ver-
sion, you will also have to run it;
then it can be deleted with a
NEW.

This is another of those cases
where it sounds more compli-

cated than it is. Try it and see.

Conclusion

Once I discovered that I was
going to have to write my own
print driver routine I was tempt-
ed to abandon the memory-
mapped I/O port and go to
straight I/O addressing. This
would have reduced the number
of ICs in the interface by two or
three since I’d only have to
decode eight bits instead of 16,
and I’d pick an I/O port, such as

FDH, that would require mini-
mum address line inversion.
Since the interface was already
built by then, I decided to leave it
alone.

I could also have reduced the
number of inverters required by
using NOR gates instead of
NAND gates for IC3. Also, I
could have reduced the +5 re-
quirements by using the 74LS
series of ICs. However, to ex-
pedite the project, I used the
chips I had on hand.

A while ago I interfaced an

RS-232-EBCD-coded Selectricto
my Sol using this same circuit.
I no longer have the Selectric,
but I’ll bet it wouldn’t take much
to get it working with the TRS-
80.

There is no good substitute
for hard copy. I hope the infor-
mation that I have provided
above and in the referenced arti-
cles will help you interface a
printer to your TRS-80. I’ll be
glad to answer any questions
that are accompanied by a self-
addressed stamped envelope. ■

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138 Microcomputing January 1980

PET &. CBM

SOFTWARE BREAKTHROUGH

MAIL LIST

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Microcomputing January 1980 139

The OSI Challenger IP MF

Just starting microcomputing? You might try this minifloppy system from Ohio Scientific.

Charles Curley
6061 Lime Ave.

Long Beach CA 90805

T he OSI Challenger IP MF
(minifloppy) is an excellent
starter system for the beginner
home computerist who wishes
to get into computing with a
maximum of ease but a mini-
mum of expense. If the beginner
wishes to expand, he can do so
with no problems, but the unit is
almost stand-alone as it comes.
With one exception, the docu-
mentation is excellent, and OSI
promises to provide user sup-
port for years to come.

Ohio Scientific has been
advertising their new C1P MF as
the first minifloppy system
available for under $1K. Strictly
speaking, it is. However, a user
will need one or two more items
in order to use the system: a TV
or monitor and perhaps a TV sig-
nal generator.

Due to FCC regulations, a
computer manufacturer cannot
sell a computer that you can just
hook up to your TV, so you have
three options: (1) buy a monitor
and take the intermediate fre-
quency signal the computer pro-
duces and feed it to the monitor;
(2) modify your present TV for
direct video signal injection (i.e.,
allow it to also function as a
monitor); or (3) buy a TV signal
generator to feed the com-
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In any case, the additional ex-
pense will run $20 to $130,
depending on which way you go
and how much quality you insist
on. Still, $1100 is impressive for
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This is definitely a bare-bones
system. Peripherals such as an
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graphics are available as extras
only. Considering that the prop-
er customer for the Challenger
IP MF is the newcomer to per-
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can say that it gives the

customer something to look for-
ward to.

This machine is clearly aimed
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painlessly as possible. One
could spend much less and buy,
say, a KIM. Then you could pro-
gram in assembly language and
hand assemble. Or you could
spend an amount comparable to
the cost of the C1P MF and buy,
say, a PET or a TRS-80. In either
case, you would still have to use
a cassette for bulk storage, with
all the hassles that cassettes
imply. A minifloppy drive for the
PET or TRS-80 would cost $400
or so, an amount the C1P MF
owner could put to other uses.

Software

In the bare-bones configura-
tion of the C1P MF, the speed
and convenience of the mini-
floppy disk is the main selling
point of the system. The user is
provided with a small DOS (disk
operating system), the Pico
DOS. With no memory expan-
sion beyond the initial 12K RAM,
the DOS supports two com-
mands: LOAD X and SAVE X,
where X is a digit from one to
eight. X defines the storage area
on the disk from which data is to
be loaded or to which it is to be
saved.

The addition of 8K more RAM
(OSI list, $138) will allow the use
of a much more extensive DOS,
Ohio Scientific’s OS-65D ($50).
This DOS supports a much more
extensive set of commands. It
allows a file structure for pro-
grams. This means that a pro-

gram can input from or write to a
file on disk (e.g., a word pro-
cessor that would rapidly fill up
the available RAM can put its
output directly onto disk, where
it has a lot more room). The
enlarged DOS supports six char-
acter names for files, rename
capabilities and other features.

The BASIC provided in the
bare-bones machine is a Micro-
soft BASIC occupying 8K of
ROM. It is 6V2 digits in precision,
has string functions, trig func-
tions and full scientific notation,
among other features. A number
of these features are not found
on other beginner’s BASICS.

The OS-65D DOS supports a
9V2 digit BASIC, which is slower
than the ROM BASIC but more
precise. This precision is
suitable for scientific or busi-
ness applications. This BASIC
occupies 12K of RAM, and the
user can software-select which
BASIC he wishes to use.

As I mentioned, OSI does not
have color graphics for the
Challenger series. They expect
to provide it as an option in the
future. The screen resolution is
256 by 256, which divides into 32
lines of 32 characters each.
However, the mechanics of tele-
visions may restrict you to 24
lines by 24 characters.

OSI software is geared to this
limitation. The characters them-
selves are eight dots by eight
and include all standard ASCII
characters. In addition, there
are 160 special characters in
ROM: gaming elements, graphic
elements and others. Any char-
acter can be invoked simply by

140 Microcomputing January 1980

The C1P, the cassette version of the C1P MF.

POKEing the appropriate
memory location with its
number. A full catalog of the
symbols available with their
numbers in decimal (for use with
BASIC) and hex (for use with
machine code) is included with
the manual.

The keyboard is totally soft-
ware controlled. This gives the
ambitious programmer much
greater flexibility than with a
hardware-controlled keyboard.
For one thing, it allows the
detection of up to eight
simultaneous key depressions.
One application of this facility
might be to program eight keys
into two pseudo-joystick
arrangements. The auto-repeat
feature of the keyboard soft-
ware is also useful.

This flexibility also allows
multiple applications of the
keys, which are not immediately
apparent. For example, in
BASIC mode, a /SHIFT/ o
deletes the last character, and a
/SHIFT/ p deletes the current
line. These two functions great-
ly facilitate program and text
editing.

One function bodes well for
the use of the C1P MF as a ter-
minal. The /SHIFT/ o function
appears on the display by insert-
ing a / (ASCII 2F), rather than
removing the offending
character. With the cost of
modems coming down, private
phone systems and micro-
oriented data networks in the

offing, many home computers
will be used as terminals as well
as stand-alone systems. OSI
designed the Cl P MF to be used
as a terminal as well as a stand-
alone, so adding this function
will be easy.

Documentation

Contrary to OSI’s reputation
for bad or nonexistent docu-
mentation, I found the C1P MF
documentation to be quite
good. I quickly found whatever
information I needed to use the
machine. The beginning BASIC
programmer will need a good
book on the system, but this is
true of any starter system. Any-
one who wishes to program in
assembly language or machine
language is similarly encour-
aged to have a good book on
6502 programming handy. The
manual does have a number of
BASIC demonstrator programs
that the user can enter and
modify for the learning ex-
perience he will gain.

A source listing of the BASIC
was noticeably missing from the
documentation. This is a result
of having Microsoft write the
BASIC; a standard part of their
contract is that no source listing
can be released by the manufac-
turer. Fortunately for the typical
user of the Cl P MF, this is not a
serious objection.

Options

A fully expanded system

could include: 32K RAM, dual
minifloppies, a cassette
recorder, a printer, a modem and
a number of other peripheral
boards. The user can buy ready-
made peripherals or build his
own.

The user who has little or no
interest in programming for
himself can purchase ready-to-
run software from OSI. Several
game disks, personal or
business disks and education
disks are already available from
OSI, with each disk containing
up to eight programs. As far as I
know, there are no other
sources for software, but this
should change as more units are
sold.

The user who wants to buy a
cassette machine now and ex-
pand up to a disk system later
should consider the C1P, the
cassette version of the C1P MF.

With only 4K of RAM and sans
cassette recorder, the unit is
otherwise identical to the C1P
MF and lists for $349. A mini-
floppy ($450), 8K of RAM ($138)
and some diskettes ($8 each)
complete the conversion.

About the only problem I had
reviewing the Challenger was
finding one! I called various
dealers in my area (southern
California) as well as Ohio
Scientific. I finally found one at
Anaheim Computer and Video,
who were most cooperative. If
you are in southern California
and wish to see a machine, give
them a call (714/995-0224).
Otherwise, call or write Ohio
Scientific (1333 S. Chillicothe
Rd, Aurora OH 44202;
216/562-3101) or OSI West
(15461 Chemical Lane, Hunt-
ington Beach CA 92649;
71 4/891 -2457). ■

TRS-80 NEEDS
FILLED

™ TRS-80 is a trademark of Radio Shack, a division of Tandy Corp.

•Disk drives— plug and run
Shugart 35 or MPI 40 track @ $319 8. Micropolis 77
track <g> $570 4-drlve cable @ $34P.P.-5” (bx of 10)
disks & $27.50 P.P.-ln hrd. case $31 P.P.

•Printers— Harris Selectrlc typewriter (refurbished) 8.
cables 8< TRS232 @ $790— new Centronics— 779
tractor @ $950 8. CENT. 730 @ $820— cable for $34
P.P.

•Professional business software— mail list &. Library
100 @ $75— letter secretary or job cost @ $240
ea.— interact inventory control with B.O.M. @ $299
Osborne interact A/R. A/P. 8, G/L ® $350— P/R @
$125— All P.P.

•Power drops outages? System boot out? Lose data?
—Get Mayday UPS (uninterruptible power supply)
from $195— write

MA. residents, add 5% tax** P.P. means postpaid
cont. U.S.A., All else F.O.B. Tewksbury* * M/C. VISA,
or check.

OMNITEK SYSTEMS

24 Marcia Jean Dr., Dept. M
Tewksbury MA 01876
-Tel. 617-851-3156.

1^-018

TRS-80

SOFTWARE

Sand for Free Software Info Packet.

• 0-01ak Syataa Only • TD-Tape or Diak Laval II •

Math/Stat Pac.'° *39.95

7 Programsi Linear, multipla, polynomial, geometrical,
exponential regression analyses. Simultaneous equations.
Bargraph with auto axis. Plot any polynomial over any
range (Reduce or Enlarge) with auto axis.

DISK . D . *14.95

The HOW TO rudements of your Disk System. Interactive
with lots of dynamic examples. Helps a beginner use
the disk system.

Hangman/ Hangfile ™ $19.95

2 Programs! Educational. Create your own dynamic
word files. User option multiple clues A subjects
with graphics. Really FUN.

Secret Words -Game!?. $17.95

3 Programsi Educational A Fun & Mind Boggling. Guess
a 2, 3, 4, 5 letter word. Review a Status options. 3
Versionsi Easiest gives lots of clues. Hardest no

C ^ U * All programs suppllad on TAPE or DATA DISKETTE
Indicate your preference and RAN sire.

Bluebird's Inc.

1441 Greenview Ave.

East Lansing. Mi. 48823 ^ B50

Michigan residents add «£ sales tax.

TRS-80"

SOFTWARE

Sand for Free Software Info Packet.
• 0-Disk System Only • TO-Tapa or Disk Laval II •

Compress - IT.? $ 24.95

2 Programsi Remove spaces A REM statements. Compresses
program into max multiple statement lines. Reduce RAN
needs up to 50%.

Simplify -IT.? $24.95

3 Programsi Lists in single statement lines. Searches A
Finds requested text or key commands. Lists all variables
used in program.

TEXT. 1 ! *49.95

A Combination Text Processor A ELECTRIC FILING CABINET.
WRITE EDIT FILE Reports, Information filesi auto Directory,
OISK store with auto Backup options. File searches by
Title or Content on 1 to 4 Disk Drives. Formats A Prints.

A SELF INDEXING QUERY SYSTEM and Word Processor.

List n File: Names & Things?. $34.95

Create and maintain NAME (customer) files. Sort using
any information category. Print lists or labels.

All programs suppllad on TAPE or DATA DISKETTE
Indicate your preference and RAM size.

Bluebird's Inc. igSfti

1441 Greenview Ave.

East Lansing. Mi. 48823

Michigan residents add *% sales tax.

^ Reader Service— see page 227

Microcomputing January 1980 141

25 START-AT-HOME
COMPUTER BUSINESSES

In "Low Capital, Startup
Computer Businesses"

CONSULTING • PROGRAMMING • MICRO COMPUTER
OPPORTUNITIES • SOFTWARE PACKAGES • FREELANCE
WRITING • SEMINARS • TAPE/DISC CLEANING • FIELD
SERVICE • SYSTEMS HOUSES • LEASING • SUPPLIES •
PUBLISHING • HARDWARE DISTRIBUTORS • SALES
AGENCIES • USED COMPUTERS • FINDER’S FEES •
SCRAP COMPONENTS • AND MORE . . .

Plus — ideas on moonlighting, going
full-time, image building, revenue
building, bidding, contracts, marketing,
professionalism, and more. No career
tool like it. Order now — if not completely
satisfied, return within 30 days for full
immediate refund.

• 8Vfe x 11 ringbound • 156 pp. • $20.00
Phone Orders 901-761-9090

DATASEARCH -d4o

incorporated

4954 William Arnold Road, Dept. A, Memphis, TN 38117
Rush my copy of "Low Capital Startup Computer Businesses” at $20.

NAME/COMPANY

ADDRESS

CITY/STATE/ZIP

□ Check Enclosed □ VISA □ Master Charge
# Exp. Date

10 MEGABYTE HARD DISK for the
[cippkz computer by Lobo

* $4990 complete

• Includes S & H in Cont. U.S.A.

• Calif, res. add 6% sales tax

* $3390 Add on drive w/ Power

Supply

• Includes S & H in Cont. U.S.A.

• Calif, res. add 6% sales tax

* Up to 16 drives per controller

* 3 ways to format the disk-
take your choice

• 1 - 10 megabyte drive

• 24-8” floppy drives

• 91 - mini floppy drives

* Hardware/ Software compatible

* Disk Diagnostics included

* Dealer inquiries invited

* Fully hardware/ software compatible. Our D.O.S. uses all of apples D.O.S.
commands in the same manner as apples, so a disk program that uses apples
disk commands will work on this hard disk.

* Winchester technology— I MI-7710 disk drive

* Lobo disk controller— Z-80 based.

* Disk diagnostics include:

• Reading & writing track & sensor

• Wild card search on catalogs which allows you to locate program titles by
using key characters of your choice.

* Up to 16 disk drivers per controller - others only allow 4

* System price $4990, includes disk drive, controller, power supply cables & disk
operating system - others cost $5350.

* Add-on disk $3390 includes additional power supply - others do not include the
power supply, they use one power supply for all drives, requiring shut down of
one drive, before power up of another.

* D.O.S. with choices, allows you to format the disk into 91 diskette sized
volumes, or 24 8” floppy sized volumes or 1 big 10 megabyte volume - others
allow you to format to 88 diskette sized volumes only.

* Manufactured by Lobo, a progressive disk drive company that is always
looking for ways to make disk drive use easier & more versatile.

14052 EAST FIRESTONE BOULEVARD
SANTA FE SPRINGS, CALIFORNIA 90670

(213)921-2111 • (714)739-0711

YOUR OWN TRS-80 SYSTEM AT TREMENDOUS SAVINGS

OTRS-80 Complete System DISK DRIVES IN STOCK!

FOREIGN and DOMESTIC DISTRIBUTORSHIPS AVAILABLE . . .

Includes: CPU/ Keyboard, Power Supply,
Video Monitor, Cassette Recorder, Manual,
and Game Cassette.

©Line Printer
©Mini Disk System
OC-10 Cassettes
©Verbatim Diskettes

REG

OUR

ITEM

PRICE

PRICE

Level II— 4k

$619.00

$575.70

Level II— 16k

$849.00

$789.60

Expansion Interface

$299.00

$278.10

Mini Disk Drive

$ 495 00

$ 385 00

Centronics 730 Printer

$ 995.00

$ 850.00

Centronics 101 Printer

$1595 00

$1400 00

Anadex DP-8000 Printer

$ 095 00

$ 99500

Memory Kit -(l6K)f ree installation $ 14900

$ 98.00

Verbatim Diskettes ea

$ 5 95

S 4 95

3

$ 17 89

$ 1200

10

$ 59 00

$ 37 00

C-10 Cassettes 5

$ 4 95

S 450

25

$ 24 75

S 10 75

Paper (9 V 2 x 1 1 fanfold.

3500 sheets)

$ 35.00

$ 29.95

CAI E7

SALE

Centronics 779

$995.00

Same as Line Printer I (Tractor)

TRS— 80 MODEL II $3626.00

• 64K RAM

• % MEG DISK

ADDITIONAL DISK DRIVE (1ST) S1069 50

ADDITIONAL DISK DRIVE (2ND i* 3RD) $ 558 00

MINI DISK DRIVES NOW $385

Over $100 less than Radio Shack s !

There are new developments every day*
write or call for the latest Information.

*^V19

777 Henderson Boulevard N-6
Folcroft Industrial Park
Folcroft PA 19032

(215) 461-5300

TOLL FREE
1 (800) 345-8102

Orders only!

142 Microcomputing January 1980

ff TT lll mmiiiiiiiiiT

SAVE SAVE SAVE SAVE SAVE SAVE Si

S "THE" >
TRS-80 Users Journal
THE 80-U.S. JOURNAL

ANYTHING you can do on (or to) Level I,
Level II or TRSDOS is covered in detail by
THE JOURNAL. (We have been doing it with
regularity since September, 1978!)
Published bi-monthly; subscriptions are
$16.00/1 year, $31.00/2 years, $45.00/3 years
in the U.S.; $20.00/1 year, $39.00/2 years,
$55.00/3 years in Canada (First class mail)
$24.00/1 year, $47.00/2 years, $68.00/3 years
all other. (Foreign sent Airmail). MC/Visa
O.K.— call (206) 475-2219 or send check or
money order to:

The 80-U.S. JOURNAL
PO Box 7112

Tacoma, Washington 98407

is* E37

If your local dealer doesn't have it, send $3.00 for a
current sample issue!) ^

wmmJT

TEXAS INSTRUMENT COMP

T I 99-4 COMPUTER

$ 995.

T I 810 BASIC PRINTER

$1590.

T I 820 BASIC PRINTER

$1990.

T I S0FTUARE

$SAVE

CENTRONICS PRINTERS

779-2 TRAC. F D

$949.

779-1 FRIC.FD

$890.

730-1 NEU PRNTR

$799.

730-3

$849.

MICRO PI $390. MICRO SI

$475.

COMMODORE BUSINESS MACHINES

PET 2001-8K

$675.

PET 2001 - 1 6N , B

$859.

PET 200 1 - 32N , B

$1090.

PET 2040 DUAL FLOPPY

$1090

PET 2022 TRAC . FD PRINTER

$849.

PET 2023 FRIC.FD PRINTER

$749.

NORTH STAR COMPUTERS
BIG $$ SAVINGS
INTERTEC SUPERBRAIN

THE HONOR GRADUATE COMPUTER

$2990

DISPLAY TERMINALS

INTERTUBE II

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HAZELTINE 1400

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1500

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28 MARLBOROUGH STREET
P0RTCAND, CONN. 06480

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V R Data Corporation, Int’l. distributor of brand name hardware,
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MINI DISK DRIVES NOW $385

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WE ARE COMMITTED TO THE TRS-80 and THE TRS-80 USERS

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•One, two, three or four drive configurations, 102k to 408k bytes.

•All systems include a patch program to upgrade your TRSDOS™ to
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FOREIGN and DOMESTIC DISTRIBUTORSHIPS AVAILABLE • TOLL FREE 1-(800) 345-8102 Orders only!

p" Reader Service— see page 227

Microcomputing January 1980 143

Chesney E. Twombly
15 Storer Street
Kennebunk ME 04043

A Heath H8 Disassembler

This article picks up where “CONOPS” (July 1979, page 108) left off.

D isassemble your Heath H8
software and learn from
the professionals. If you want
to educate yourself in the art of
programming, this is one of the
most productive exercises you
can perform.

I have anticipated this need
of H8 owners and present this
disassembler, which will run on
your versatile Heath machine
without using up a lot of that
expensive memory. You are
already familiar with “CON-
OPS,” the H8 console-oriented
operating system (July 1979
Microcomputing , p. 108). This
disassembler uses many CON-
OPS subroutines and has been
cunningly designed to occupy a
block of adjacent memory,
which makes permanent at-
tachment easy.

What Does It Do?

A disassembler looks at a
program stored in memory and
helpfully translates each in-
struction byte from binary code

CONOPS, including the disassembler and
string finder, is available from the author
for $5 (one per customer). It comes on cas-
sette in H8 memory image format, assem-
bled to start at any requested address be-
tween 2700 and B700.

into the mnemonic language
used by assemblers. Just tell
“Sammy” where to begin and
he will print the instruction ad-
dress, the hexadecimal instruc-
tion and the corresponding
mnemonic.

Sammy will not give you
labels or remarks and can deal
only with instruction codes.
Data bytes (ASCII characters,
for example) are not recog-
nized. Sammy assumes every-
thing is an instruction and will
print garbage when data is
encountered. On a straight op
code diet, he will make no er-
rors and, fortunately, will
recover in a couple of bytes
when meeting instruction bytes
again after being brought down
by data.

How to Use It

Load the program into your
H8, byte by byte. It will take
some time, but the listing is in
hexadecimal, so you can use
the efficient CONOPS program
loader referenced earlier. To
run the disassembler, hit G for
GO and enter67DF, thestarting
address. You will then see the
following display:

BEGIN ADDR?

Now, enter the address of the
first byte of the program you
wish to disassemble. Take care
to start it on the first byte of an
instruction code. If you enter
6C00, the start of CONOPS, you
will be rewarded with a display
as follows:

6C00C3C1 6E JMP

Push any key other than A or S
to decode the next instruction:

6C03 7E MOV A,M

If you want to save yourself
the trouble of pushing a key to
advance the disassembler, you
can press the A key, which will
change the mode to automatic.
The program will then do its
own stepping and can be
stopped only by a reset applied
from the H8 front panel keypad.
The automatic mode is useful if
you have a printer. In the one-
step mode, entering an S will
stop the program and exit to
***, the operating system
ready prompt.

How Does It Work?

Look at an 8080 op code table,
like the one on the large plastic
card that comes with your H8,
and you will see that the mne-

1

INST

SPACE

» I

MNEM

CNT

CNT

CNT

Fig. 2.

monies have a curious variety.
The character count of the main
word ranges from 2 to 4. Ap-
pended characters number 0 to
4. Many bytes of any disas-
sembler are used by the mne-
monic lookup tables. For each
of the 244 op codes, the program
must contain the following data:
the mnemonic, coded in ASCII;
formatting information; and in-
struction byte count.

A single lookup table holding
all this data would use about
1400 bytes of memory. Such a
table would contain many
repetitive words. For example,
MOV appears in 63 instructions;
the appended letter B appears in
45. Avoiding as much of this
wasteful duplication as possi-
ble was one of the main con-
siderations in the design of this
disassembler program.

Studying the op code table
reveals some useful facts.

1 . Bits 6-7 of the op code iden-
tify certain subgroups. In split-
octal, these two bits are 0, 1 , 2 or
3.

2. All codes starting with 1 or
2 are single-byte instructions.

3. All codes in octal group
100-177, with one exception, are
MOV instructions.

4. Codes in octal 200-277 are
combinations of eight 3-char-
acter, basic mnemonic words
plus eight single-character
operands.

] [

INDEX I I MNEM I I MNEM

Fig. 1.

144 Microcomputing January 1980

YES

GET THE
OP COOE PLUS
THE NEXT TWO
BYTES.

USE OP CODE
TO ACCESS THE
LOOKUP TABLE
OPSOOO/OPSSOO

In this program, the lookup
tables have a total byte count
of 606. The large, general table,
OPS000/OPS300, has the ar-
rangement shown in Fig. 1.

The index byte has a most
significant bit of 1, which makes
it identifiable as a non-mne-
monic. The table is scanned
starting at the high-end address
—the location called STSCAN
in the Disassembler program
listing. When the index byte is
encountered, the next byte
down is an op code byte, which
is compared with the instruction
byte held in Reg A. When a
match is found, the table pointer
is advanced to decode the index
byte and then to read the mne-
monic and place it in the output
buffer LIN. The table contains
no spaces. Space information is
in the index byte.

The index byte is encoded as
shown in Fig. 2. MNEM CNT is
the total number of characters
in the mnemonic, excluding
spaces. It may be 2 to 7. SPACE
CNT is the number of spaces be-
tween the main mnemonic word

Fig. 3. Program flowchart.

and any appended operand. It
may be zero to 3. INST CNT is
the number of bytes in the in-
struction. It may be 1 to 3.

Two other tables are used.
OPS200 serves the octal group
200-277 and is used, in a limited
way, by groups 000 and 100. The
remaining table supplies mne-
monics for the instructions INR,
DCR, M VI, MOV and HLT.
OPS200 is accessed by the
subroutines GET1, GET3 and
ADDONE.

The flowchart in Fig. 3 gives
an overall view of the program
structure, which is simple and
easy to follow. DECODE is a
subroutine, with a return at the
end of each branch. It is called
by the main program and comes
back with the status of the carry
flag controlling the next step.

I have found the disassembler
useful not only in the analysis of
unknown programs, but also in
checking for loading errors. You
can add another code to your
CONOPS jump table to select
the disassembler. I use S for
“Sammy.” ■

* DISASSEMBLER FOR HEATH H8 COMPUTER

*

* FOR USE WITH "CONOPS", THE H8 CONSOLE

* ORIENTED OPERATING SYSTEM. SEE KILOBAUD.

*

* BY CHESNEY E. TUOMBLY

* 15 ST0RER ST.,

* KENNEBUNK ME 04043

10

*

2/11/79

11

*

12

*

13

OPT

MEM, NUM

14

*

15

6F3E

ORG

♦6F3E

16

*

17

6FB0

STACK

EQU

$6FB0

18

6DB4

MSI

EQU

I6PB4

19

6C03

PDATA

EQU

$6C03

20

6C4C

IN4H

EQU

S6C4C

21

6C11

CRLF

EQU

I6C 1 1

22

6C1D

INCHR

EQU

♦ 6C1B

23

6EDB

NONIT

EQU

$6EDB

24

6C55

HEXL

EQU

$6C55

25

6C59

HEXR

EQU

♦ 6C59

26

*

27

6F3E

MCNT

DS

1

28

6F3F

MODE

DS

1

29

6F40

ADDM

DS

2

30

6F42

ADDR

DS

2

31

6F44

INST

DS

1

32

6F45

OPER

DS

2

33

6F47

NBR

DS

1

34

6F48

LIN

DS

27H

35

*

36

67DF

ORG

$67DF

37

*

38

* MAIN

PROGRAM

39

*

40

67DF

31

R0 6F

ENTER

LXI

SP, STACK

41

67E2

21

B4 6D

LXI

H,MS1

42

67E5

CD

03 6C

CALL

PDATA

43

67E8

3E

FF

HVI

A,*FF

44

67EA

32

3F 6F

STA

MODE

45

67ED

CD

4C 6C

CALL

IN4H

46

67F0

EB

XCHG

47

67F1

22

42 6F

SHLD

ADDR

48

67F4

E5

CONTIN

PUSH

H

49

67F5

CD

8E 69

CALL

SPACES

50

67F8

El

POP

H

51

67F9

7E

MOV

A,M

52

67FA

32

44 6F

STA

INST

53

67FD

23

INX

H

54

67FE

7E

MOV

A,N

55

67FF

32

45 6F

STA

OPER

56

6802

23

INX

H

57

6803

7E

NOV

A,M

58

6804

32

46 6F

STA

OPER+1

59

6807

21

48 6F

LXI

H,LIN

60

680A

3A

43 6F

LDA

ADDR+1

JPRESET STEP MODE
,*GET START ADDR
;H,L < D,E
; SAVE IT
JSTACK < ADDR

JH,L < ADDR
J6ET OPR Ml
; SAVE IT

JGET OPR #2
JSAVE

J6ET OPR #3
; SAME

JPNTR TO START OF BUFR
JGET ADDR HI BYTE

Microcomputing January 1980 145

Disassembler program.

61

680D

CD

71

69

CALL

CBH

JCONVT BINARY TO HEX

163

68AF

AF

XRA

A

JHARDUARE RESET

62

6810

3A

42

6F

LDA

ADDR

; LO BYTE

164

68B0

32

3 F

6F

STA

MODE

63

6813

CD

71

69

CALL

CBH

JCONVT AND PUT IN BUFR

165

68B3

2A

42

6F

AUTO

LHLD

ADDR

64

6816

CD

69

68

CALL

DECODE

J PROCESS BYTE

166

68B6

C3

F4

67

JMP

CONTIN

65

6819

DA

74

68

JC

OUTLIN

JHAVE COMPLETE MNEMONIC

167

*

66

*

168

♦ INSTR

CODE HI

BYTE IS

CLASSIFIED TO

67

* ENTERED WHEN OPCODE REQUIRES USE OF

169

* DETERMINE UHICH PROCESSING ROUTINE

68

* TABLES OPS000 OR OPS300

TO GET MNEMONIC.

170

♦ UILL

BE USED

TO GET MNEMONIC AND BYTE

69

*

171

* COUNT

. RETURN

1 TO CALLING PROGRAM.

70

681 C

21

CF

6B

LXI

H,STSCAN

JPNTR TO SCAN START

172

*

71

681 F

3A

44

6F

LDA

INST

; GET 1ST OPCODE BYTE

173

68B9

3E

01

DECODE

MVI

M

72

6822

F5

XSCAN

PUSH

PSU

174

68BB

32

47

6F

STA

NBR

73

6823

26

SCAN

DCX

H

175

68BE

3A

44

6F

LDA

INST

74

6824

7E

NOV

A, M

176

68C1

07

RLC

75

6825

D6

80

SUI

$80

J INDEX BYTE TEST

177

68C2

07

RLC

76

6827

FA

23

68

JH

SCAN

J NOT INDEX SO LOOP

178

68C3

E6

03

ANI

3

77

682 A

FI

POP

PSU

179

68C5

D6

02

SUI

2

78

682B

26

DCX

H

JPNTR TO OPCODE BYTE

180

68C7

CA

3A

69

JZ

GR2

79

682C

BE

CHP

H

; COMPARE 1ST INSTRUCTION BYTE

181

68CA

F0

RP

80

682D

CA

33

68

JZ

FOUND

J TO TABLE OPCODE BYTE.

182

68CB

C6

01

ADI

1

81

6830

C3

22

68

JHP

XSCAN

; LOOK FOR NEXT OPCODE BYTE

183

68CD

CA

06

69

JZ

GR1

82

*

184

*

83

6833

23

FOUND

INX

H

185

68D0

3A

44

6F

GR0

LDA

INST

84

6834

7E

MOV

A , M

GET INDEX BYTE FROM TABLE

186

68D3

E6

07

ANI

7

85

6835

F5

PUSH

PSU

187

68D5

FE

04

CPI

4

; TEST FOR INR

86

6836

F5

PUSH

PSU

188

68D7

C2

E3

68

JNZ

TDCR

87

6837

E6

07

ANI

7

J GE T MNEM BYTE COUNT

189

68DA

11

F0

6B

LXI

B, INR

88

6839

32

3E

6F

STA

MCNT

SAVE IT HERE

190

68DD

CD

60

69

CALL

GET3

89

683C

47

MOV

6, A

;AND HERE

191

68E0

C3

7E

69

JMP

ADDONE

90

68 3D

FI

POP

PSU

GET INSTR BYTE

192

*

91

683E

•F

RRC

193

68E3

FE

05

TDCR

CPI

5

92

683F

0F

RRC

194

68E5

C2

FI

68

JNZ

TMVI

93

6840

0F

RRC

195

68E8

It

F3

6B

LXI

B t BCR

94

6841

E6

03

ANI

3

J GET SPACE COUNT

196

68EB

CD

60

69

CALL

GET3

95

6843

47

MOV

B,A

197

68EE

C3

7E

69

JMP

ADDONE

96

6844

4F

MOV

C,A

198

*

97

6845

3E

05

MV I

A , 5

;COMPUTE N BYTES IN

199

68F1

FE

06

TMVI

CPI

6

98

6847

90

SUB

6

JMNEMONIC MAIN UORD.

200

68F3

C2

04

69

JNZ

GR000

99

6848

47

MOV

6, A

J SAVE WORD COUNT IN B

201

68F6

3E

02

MVI

A, 2

100

6849

FI

POP

PSU

202

68F8

32

47

6F

STA

NBR

101

684A

C5

PUSH

6

203

68FB

1 1

F 6

6B

LXI

B,MVI

102

684B

07

RLC

204

68FE

CD

60

69

CALL

GET3

103

684C

07

RLC

205

6901

C3

7E

69

JMP

ADDONE

104

684D

07

RLC

206

*

105

684E

E6

03

ANI

3

207

6904

A7

GR000

ANA

A

{CLEAR CARRY

106

6850

32

47

6F

STA

NBR

208

6905

C9

RET

107

*

209

*

108

* TAKE

MNEMONIC FROM LOOK

-UP TABLE

210

6906

3A

44

6F

6R1

LDA

INST

109

* AND

PUT IT

INTO OUTPUT

BUFFER (LIN).

211

6909

FE

76

CPI

*76

{TEST FOR HLT

110

* INSERT ANY

REQUIRED SPACES.

212

690B

C2

16

69

JNZ

ISMOV

111

*

213

690E

11

FC

6B

LXI

D,HLT

112

6853

11

62

6F

LXI

B.LIN+26

214

6911

CD

60

69

CALL

GET3

113

6856

23

CHAR

INX

H

215

6914

37

STC

114

6857

7E

MOV

A,M

216

6915

C9

RET

115

6858

12

STAX

D

217

*

116

6859

13

INX

D

218

6916

F5

ISMOV

PUSH

PSU

117

685A

05

DCR

6

219

6917

F5

PUSH

PSU

118

6856

C2

56

68

JNZ

CHAR

220

6918

11

F9

6B

LXI

D,HOV

119

685E

13

SPAC

INX

D

221

691 B

CD

60

69

CALL

GET3

120

685F

0D

DCR

C

222

691E

FI

POP

PSU

121

6860

C2

5E

68

JNZ

SPAC

223

691 F

E 6

38

ANI

$38

122

6863

3A

3E

6F

LDA

MCNT

224

6921

0F

RRC

123

6866

Cl

POP

B

225

6922

0F

RRC

124

6867

90

SUB

6

226

6923

0F

RRC

125

6868

CA

74

68

JZ

OUTLIN

227

6924

CD

54

69

CALL

6ET1

126

68 6 B

47

MOV

B, A

228

6927

32

67

6F

STA

LIN+31

127

686C

23

APND

INX

H

229

692A

3E

2C

MVI

A i ' r '

128

686D

?E

MOV

A,M

230

692C

32

68

6F

STA

LIN+32

129

686E

12

STAX

D

231

692F

FI

POP

PSU

130

686F

13

INX

D

232

6930

E6

07

ANI

7

131

6870

05

DCR

6

233

6932

CD

54

69

CALL

6ET 1

132

6871

C2

6C

68

JNZ

APND

234

6935

32

69

6F

STA

LTN+33

133

*

235

6938

37

STC

134

* PUT

INSTRUCTION CODE INTO OUTPUT

236

6939

C9

RET

135

* BUFR

AND PRINT CONTENTS OF BUFFER.

237

*

136

*

238

693A

3A

44

6F

GR2

LDA

INST

137

6874

3A

47

6F

OUTLIN

LDA

NBR

239

693D

F5

PUSH

PSU

138

6877

47

MOV

B,A

240

693E

11

D0

6B

LXI

D,OPS200

139

6878

11

44

6F

LXI

D, INST

241

6941

E6

38

ANI

$38

140

6876

21

4E

6F

LXI

H,LIN+6

242

6943

fF

RRC

141

687E

1 A

ANOTH

LDAX

D

243

6944

81

ADC

E

142

687F

CD

71

69

CALL

CBH

244

6945

5F

MOV

E,A

143

6882

05

DCR

6

245

6946

CD

60

69

CALL

GET3

144

6883

13

INX

D

246

6949

FI

POP

PSU

145

6884

23

INX

H

247

694A

E6

97

ANI

7

146

6885

E5

PUSH

H

248

694C

CD

54

69

CALL

SET 1

147

6886

2A

42

6F

LHLD

ADDR

249

694F

32

67

6F

STA

LIN+31

148

6889

23

INX

H

250

6952

37

STC

149

688A

22

42

6F

SHLD

ADDR

251

6953

C9

RET

150

688D

El

POP

H

252

*

151

688E

C2

7E

68

JNZ

ANOTH

253

6954

11

D0

6B

GET1

LXI

D ,OPS200

152

6891

CD

11

6C

CALL

CRLF

; ALL DATA IN LIN

254

6957

13

INX

D

153

6894

21

48

6F

LXI

H, LIN

J PREPARE TO OUTPUT IT.

255

6958

13

INX

D

154

6897

CD

03

6C

CALL

PDATA

256

6959

13

INX

D

155

689A

3A

3 F

6F

LDA

MODE

257

695A

07

RLC

156

689D

FE

FF

CPI

IFF

J TEST MODE BYTE

258

695B

RLC

157

689F

C2

B3

60

JNZ

AUTO

}00 INDICATES AUTOMATIC

239

695C

01

ADC

E

158

68A2

CD

ID

6C

CALL

INCHR

JUAIT FOR OPER CMND

260

695D

5F

MOV

E,A

159

66A5

FE

53

CPI

'S'

; TEST FOR STOP COMND

261

695E

1 A

LDAX

D

160

68A7

CA

DB

6E

JZ

MONIT

262

695F

C9

RET

161

68AA

FE

41

CPI

'A'

J TEST FOR AUTO COMND. AUTO

263

*

162

68AC

C2 83

68

JNZ

AUTO

J MODE CAN BE EXITED ONLY BY

264

6960

06

03

GET3

MVI

B,3

146 Microcomputing January 1980

265

6962

21

CM

-O

6F

LXI

H , L IN+26

355

6A14

20

B3

DB

♦20 , M3

266

6965

1 A

GETHOR LDAX

B

356

6A1 6

2A

2A

2A

DB

'***'

267

6966

77

00V

M, A

357

6A1 9

21

F4

DB

*2»,*F4

268

6967

13

I NX

B

358

6A1B

4C

58

4?

DB

axiH-

26?

6968

23

INX

H

6A1E

48

270

6969

05

BCR

B

359

6A1F

22

EC

DB

♦22, $EC

271

696 A

CA

70

69

JZ

DONE

360

6A21

53

48

4C

DB

SHLD '

272

696D

C3

65

6?

JMP

GETMOR

6A24

44

273

6970

C9

DONE RET

361

6A25

23

B4

DB

♦23 , M4

274

*

362

6A27

4?

4E

58

DB

'INXH'

275

* CONVERT BINARY BYTt IN REG A TO 2 HEX

6A2A

48

276

* CHARS. SAVE

IN ADDR POINTED TO BY H,L .

363

6A2B

27

B3

DB

♦ 27, ♦ B 3

277

*

364

6A2D

44

41

41

DB

•" DA A •'

278

6971

F5

CBH PUSH

PSU

365

6A30

28

B3

DB

♦ 28, M3

279

6972

CD

55

6C

CALL

HEXL

366

6A32

2A

2A

2 A

DB

280

6975

77

HOV

M f A

367

6A35

29

B4

DB

♦2? , M4

281

6976

FI

POP

PSU

368

6A37

44

41

44

DB

'DADH'’

282

6977

23

INX

H

6A3A

48

283

6978

CD

59

6C

CALL

HEXR

369

6A3B

2A

EC

DB

♦2A, ♦EC

284

697B

77

MOV

M

370

6A3D

4C

48

4C

DB

•'LHLD /

285

697C

23

INX

H

6A40

44

286

697D

C?

RET

371

6A41

2B

B4

DB

♦ 2B,M4

287

*

372

6A43

44

43

58

DB

' DCXH

288

697E

3A

44

6F

ADDONE LDA

INST

6A46

48

28?

6981

E6

38

AH I

♦ 38

373

6A47

2F

B3

DB

♦2F , M3

290

6983

IF

RAR

374

6A49

2A

2A

2A

DB

■'***'

291

6984

IF

RAR

375

6A4C

31

F5

DB

♦ 31 ,M5

292

6985

IF

RAR

376

6A4E

4C

58

49

DB

LX ISP

293

6986

CD

54

69

CALL

GET1

6A51

53

50

294

698?

32

67

6F

STA

LIN+31

377

6A53

32

F3

D B

♦32, ♦FS

295

698C

37

STC

378

6A55

53

54

41

DB

'STA'

296

698D

C9

RET

379

6A58

33

B5

DB

♦33 , M5

297

*

380

6A5A

49

4E

58

DB

' INXSP

298

* FILL OUTPUT

BUFR WITH ASCII SPACE CHARS.

6A5D

53

50

29?

*

381

6A5F

37

B3

DB

♦37, M3

300

698E

21

48

6F

SPACES LXI

H,LIN

382

6A61

53

54

43

DB

'STC /

301

6991

06

27

NVI

B, 127

383

6A64

38

B3

DB

♦ 38, M3

302

6993

36

20

SP MV I

M20

384

6A66

2A

2A

2A

DB

■'***'

303

6995

05

DCR

B

385

6A69

39

B5

DB

♦ 39, M5

304

6996

23

INX

H

386

6A6B

44

41

44

DB

DADSP "

305

6997

C2

93

69

JNZ

SP

6A6E

53

50

306

699A

3E

04

MV I

A t 4 ; END OF LINE CHAR

387

6A70

3A

F3

DB

♦3A,IF3

307

699C

32

6F

6F

STA

LIN.+ 39

388

6A72

4C

44

41

D B

'LDA

308

699F

C9

RET

389

6A75

3B

B5

DB

♦3B,$B5

309

*

390

6A77

44

43

58

DB

'DCXSP'

310

69A0

ORG

♦ 69A0

6A7A

53

50

311

*

391

6A7C

3F

B3

DB

♦ 3F, M3

312

* MNEMONIC LOOK-UP TABLES.

392

6A7E

43

4D

43

DB

' CMC'

313

*

393

* OPS300

314

♦ OPS000

394

6A81

C0

B3

DB

♦ C0,M3

315

69A0

00

B3

DB

0,M3

395

6A83

52

4E

5A

DB

'RNZ'

316

69A2

4E

4F

50

DB

• NOP'

396

6A86

Cl

B4

DB

♦Cl ,M4

317

69A5

01

F 4

DB

1 , 4F4

397

6A88

50

4F

50

DB

'POPB '

318

69A7

4C

58

4?

DB

axiB'

6A8B

42

69AA

42

398

6A8C

C2

F3

DB

♦C2,M3

31?

69AB

0 2

AD

BB

2,$AD

399

6A8E

4A

4E

5A

DB

JNZ'

320

69 AD

53

54

41

DB

■'STAXB'

400

6A91

C3

F3

DB

♦C3,IF3

69B0

58

42

401

6A93

4A

4D

50

DB

' JHP

321

69B2

03

B4

DB

3,M4

402

6A96

C4

F3

DB

♦C4,IF3

322

69B4

49

4E

58

DB

'INXB'

403

6A98

43

4E

5A

DB

■ CNZ'

69B7

42

404

6A9B

C5

AD

DB

♦C5, ♦AD

323

69B8

07

B3

BB

7, M3

405

6A9D

50

55

53

DB

'■PUSHB '

324

69BA

52

4C

43

BB

-*RLC"

6AA0

48

42

325

69BB

08

B3

DB

♦ 8, M3

406

6AA2

C6

D3

DB

♦ C6,M3

326

69BF

2A

2A

2A

DB

* #**'■

407

6AA4

41

44

4?

DB

•ADI'

327

69C2

09

B4

DB

♦9,*B4

408

6AA7

C7

B4

DB

♦C7,M4

328

69C4

44

41

44

DB

/ DADB /

409

6AA9

52

53

54

DB

-RST0

69C7

42

6AAC

30

329

69C8

0A

AD

DB

S A r $ AD

410

6AAD

C8

BA

DB

♦C8,IBA

330

69CA

4C

44

41

DB

'LDAXB'

411

6AAF

52

5A

DB

'RZ'

69CB

58

42

412

6AB1

C9

B3

DB

♦C?,iB3

331

69CF

0B

B4

DB

♦ B,M4

413

6AB3

52

45

54

DB

RET'

332

69D1

44

43

58

DB

'DCXB

414

6AB6

CA

FA

DB

♦CA, ♦FA

69D4

42

415

6AB8

4A

5A

DB

JZ'

333

69D5

0F

B3

DB

♦ F, M3

416

6ABA

CB

B3

DB

♦ CB , M3

334

69D7

52

52

43

DB

'RRC'

417

6ABC

2A

2A

2A

DB

335

69DA

10

B3

DB

♦ 10, i B 3

418

6ABF

CC

FA

DB

♦ CC , MA

336

69DC

2A

2A

2A

DB

419

6AC1

43

5A

DB

"c r

337

69BF

11

F4

DB

♦ 1 1 , M4

420

6AC3

CD

EC

DB

♦CD, ♦EC

338

69E1

4C

58

49

DB

'LXID'

421

6AC5

43

41

4C

DB

'CALL--

69E4

44

6AC8

4C

339

69E5

12

AD

DB

♦12, ♦AD

422

6AC9

CE

D3

DB

♦CE,M3

340

69E7

53

54

41

DB

'STAXD'

423

6ACB

41

43

49

DB

'ACT

69EA

58

44

424

6ACE

CF

B4

DB

♦ CF,M4

341

69EC

13

B4

BB

♦ 1 3, M4

425

6AD0

52

53

54

DB

'RST 1 '

342

69EE

49

4E

58

DB

'INXD '

6AD3

31

69F 1

44

426

6AD4

D0

B3

DB

M0, M3

343

69F2

17

B3

DB

♦17, $B3

427

6AD6

52

4E

43

DB

'RNC'

344

69F4

52

41

4C

DB

/ RAL /

428

6AD9

D1

B4

DB

Ml ,M4

345

69F7

18

B3

DB

♦ 18, M3

42?

6ADB

50

4F

50

DB

•'POPD '

346

69F9

2A

2A

2A

DB

'***''

6ADE

44

347

69FC

1?

B4

DB

$19, ♦BA

430

6ADF

D2

F3

DB

M2, M3

348

69FE

44

41

44

DB

"DADD-'

431

6AE1

4A

4E

43

DB

'JNC'

6A0 1

44

432

6AE4

D3

D3

DB

♦ D 3 , ♦ D 3

349

6A02

1 A

AD

DB

♦1A,$AD

433

6AE6

4F

55

54

DB

'OUT'

350

6A04

4C

44

41

DB

"LBAXD''

434

6AE9

D4

F3

DB

♦ D4,M3

6A07

58

44

435

6AEB

43

4E

43

DB

'CNC'

351

6A0?

IB

B4

DB

♦ 1B,M4

436

6AEE

D5

AD

DB

♦D5,MD

352

6A0B

44

43

58

DB

'■DCXD-'

437

6AF0

50

55

53

DB

•PUSHD'

6A0E

44

6AF3

48

44

353

6A0F

IF

B3

DB

♦ IF, M3

438

6AF5

D6

D3

DB

♦ D6, M3

354

6A1 1

52

41

52

DB

'•RAR'

439

6AF7

53

55

4?

DB

'SUI'

Microcomputing January 1980 147

440

6AFA

87

84

BB

*87,184

441

6AFC

52

53

54

BB

R5T2'

6AFF

32

442

6B00

88

8A

88

*D8,*BA

443

6802

52

43

88

RC'

444

6804

89

83

DB

♦D9 , IB3

445

6806

2A

2A

2A

88

'***'

446

6809

8 A

FA

D8

♦DA,*FA

447

6808

4A

43

88

'JC'

448

6808

88

DA

DB

♦DB,4DA

449

680F

49

4E

8B

•'IN

450

6811

8C

FA

DB

♦DC , *FA

451

6813

43

43

88

'CC'

452

6815

88

83

IiB

*DD,*B3

453

6817

2A

2A

2A

88

***'

454

681 A

BE

83

D8

*> D E , * 8 3

455

681 C

53

42

49

88

5BI '

456

68 1 F

BF

84

I'B

*DF , *84

457

6821

52

53

54

88

RST3'

6824

33

458

6825

E0

83

88

♦Efl, *D3

459

6827

52

50

4F

88

RPG

460

682A

El

84

88

♦El , 484

461

682C

50

4F

50

88

'POPH

6B2F

48

462

6830

E2

F3

BB

♦E2,*F3

463

6B32

4A

50

4F

BB

JPO'

464

6835

E3

AC

DB

$E3f $AC

465

6837

58

54

48

88

'XTHL'

683A

4C

466

6838

E4

F3

DB

*E4 , *F3

467

683D

43

50

4F

D8

•CPD

468

6840

E5

AD

DB

*E5,IAD

469

6842

50

55

53

88

' PUSHH

6845

48

48

470

6847

E6

83

DB

♦E6, 6D3

471

6849

41

4E

49

DB

AMI

472

684C

E7

84

DB

♦E7 , *84

473

684E

52

53

54

88

'RST4-

6851

34

474

6852

E8

B3

8 8

♦E8,*B3

475

6854

52

50

45

DB

'RPE

476

6857

E9

AC

DB

♦E9, 4AC

477

6B59

50

43

48

DB

'PCHL '

685C

4C

478

685D

EA

F3

88

IEA.IF3

479

685F

4 A

50

45

D8

' JPE'

480

6862

E8

AC

8 8

♦EB , *AC

481

6864

58

43

48

DB

'XCHG '

6867

47

482

6868

EC

F3

DB

♦EC, *F3

483

6B6A

43

50

45

DB

CPE

484

6B6D

EB

83

88

♦ED, *83

485

6B6F

2A

2A

2A

88

486

6872

EE

83

88

*EE.*D3

487

6874

56

52

49

DB

'XRI'

488

6877

EF

84

DB

♦EF, 4B4

489

6879

52

53

54

88

RST5

6B7C

35

490

6B7B

F0

BA

DB

♦F0,*BA

491

6B7F

52

50

DB

RP

492

6881

FI

86

DB

♦FI ,*Bo

493

6883

50

4F

50

DB

POPPSU'

6886

50

53

57

494

6B89

F2

FA

DB

♦F2,*FA

495

6888

4A

50

88

•"JP

496

6888

F3

8A

DB

*F3,*BA

497

6B8F

44

49

DB

or

498

6891

F4

FA

DB

♦F4, ♦ FA

499

6893

43

50

88

•CP

500

6895

F5

AF

DB

*F5,*AF

501

6897

50

55

53

DB

PUSHPSU

6B9A

48

50

53

6898

57

502

6B9E

F6

83

DB

♦F6, 4D3

503

68A0

4F

52

49

DP

ORI'

504

68A3

F7

84

DB

*F7 , *84

505

68A5

52

53

54

D8

RST6'

6FA8

36

506

6BA9

F8

BA

PB

♦F8, *BA

507

68AB

52

48

88

508

68AD

F9

AC

DB

*F9 , *AC

509

6BAF

53

50

48

DB

'SPHL'

6882

4C

510

6683

FA

FA

DB

♦FA, *FA

511

6885

4A

48

DB

Jrt

512

6687

FB

8A

88

♦FB, ♦BA

513

6BB9

45

49

88

'll'

514

6888

FC

FA

DB

♦FC , *FA

515

6888

43

48

88

CM'

516

6BBF

F8

83

DB

♦FD, 4B3

517

68C1

2A

2A

2A

88

518

68C4

FE

83

DB

♦FE , *D3

519

68C6

43

50

49

88

'CPI'

520

6BC9

FF

84

DB

♦FF , *84

521

6BCB

52

53

54

88

RST7'

6BCE

37

522

*

523

6BCF

STSCAN

DS

1

524

*

525

6880

41

44

44

OPS200

DB

• ADDB '

6883

42

526

6884 41
6887 43

44 43

88

ADCC'

527

6888 53
6888 44

55 42

DB

'5UBD '

528

6BDC 53
6BDF 45

42 42

DB

'SBBE'

529

68E0 41
68E3 48

4E 41

DB

'ANAH'

530

6BE4 58
6BE7 4C

52 41

DB

'XRAL

531

68E8 4F
6BEB 48

52 41

DB

'ORAM-

532

6BEC 43
68EF 41

48 50

DB

'CNPA'

533

*

534

6BF0 49

4E 52

INR

DB

'INR'

535

6BF3 44

43 52

DCR

D8

'DCR'

536

6BF6 48

56 49

HVI

DB

'MVI'

537

* •

538

6BF9 48

4 F 56

MOV

DB

'NOV '

539

6BFC 48

4C 54

HLT

88

HLT'

540

*

541

END

SYHBOL

TABLE:

ADDM

6F4#

ADDONE 697E

APDR

6F42

ANOTH

687E

APND

686C

AUTO

68B3

CBH

6971

CHAR

6856

CONTIN

67F4

CRLF

6C1 1

DCR

6BF3

DECODE 68B9

DONE

6970

ENTER

67DF

FOUND

6833

GET1

6954

GET3

6960

GETHOR 6965

GR0

6880

GR000

6904

GR1

6906

GR2

693A

HEXL

6C55

HEXR

6C59

HLT

6BFC

I N4H

6C4C

INCHR 6C1D

INR

6BF0

INST

6F44

ISMOV

6916

LIN

6F48

MCNT

6F3E

NODE

6F3F

HONIT

6ED6

MOV

6BF9

MSI

6884

HVI

68F6

NBR

6F47

OPER

6F45

OPS200

6880

OUTLIN

6874

PDATA 6C03

SCAN

6823

SP

6993

SPAC

685E

SPACES

698E

STACK 6FB0

STSCAN 6BCF

TDCR

68E3

THVI

68F 1

XSCAN

6822

Note: CONOPS works only with the H8 console driver as originally supplied by Heath.
The new console driver, used in the H8-18 software package (Heath’s #890-3-3), is differ-
ent and I don’t know how to use it yet.

Main/Frames $200

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148 Microcomputing January 1980

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38W255 Deerpath Rd.
Batavia IL 60510

Software Clock
for the 6800

With this routine, you have instant access to the correct date and time — in ASCII format.

•

SOFTWARE

CLOCK PROGRAM

A000

IRQ

EQU

• A000

8101

PIA0OB

EQU

• 8101

PTA B PORT

DATA REGISTER

8109

PIA0CB

ECU

• 8109

p i a Control register b port

8300

CIOS

EQU

• 8300

ACTA CONTROL AND STATUS REGISTER

8301

Cl 90

EQU

CIOSm

Data register of acIa

0800

ORB

• 800

0800

KTImE

RmB

1

VARIABLE TO COUNT 60 HZ INTERRUPT

0801

U0AV1

TDAY1

RmB

1

0803

Rmb

1

0803

UM9N1

RMB

1

0804

48

52

20

20

HR

FCC

/HR */

imihenever a computer is in-
W terfaced to the real world

0808

0809

2A

40

49

4E

20

Ml N

Fee

/MIN •/

080D

2A

080E

53

45

43

2o

SEC

Fee

/SEC #/

via sensors or a controllable de-

0812

2A

0813

0817

AD

2 A

4F

20

2o

M8

Fee

/M0 •/

vice, there is often a need for the

0818
081 C

44

2A

41

59

20

day

Fee

/DAY */

computer to know what time it

0810

0821

59

2A

52

20

20

YR

Fee

/YR */

is. Controlling a particular de-

♦

Pec

vice at a specific time is one

0822

20

20

DT

/ /

0824

30

THRS

FCB

• 30

such use (for example, turning

0825

0826

30

3A

UHRB

FCB

Fee

• 30
/!/

home lights on or off).

0827

0828

30

30

TMIM

umjn

FCB

FCB

• 30

• 30

Another use might be append-

0829

082A

3A

30

TSEC

Fee

FCB

/!/
• 30

ing the time to a particular

082B

082C

30

20

20

20

20

usee

FCB

FCC

• 30
/

event. My need fell into this lat-

0830

0831

20

30

TM0N

FCB

• 30

ter category. In my computer-

0832

0833

0834

30

or

umbn

FCB

FCB

FCB

• 30
•2F
•30

SLASH

controlled security system, 1 am

cr

30

tday

able to append both the time

0835

0836

30

2F

UDAY

FCB

FCB

• 30

• 2F

SLASH

and the date to an event. For ex-

0837

0838

30

30

tyrs

UYRS

FCB

FCB

• 30

• 30

ample, if the telephone or door-

0839

00

00

OA

2a

FCB

•0D/*00iP0Aj l#

bell rings, the event will be noted

Listing 1. Assignment of variables for the remainder of the pro-
gram. A terminal interfaced to an ACIA at $8300 is indicated, as
well as a PI A at $8101 through which the interrupts are serviced.
The ASCII time and date sentence is shown beginning at $0822.

on a printer along with the time
and date.

My second need for a real-
time clock was for an amateur
radioteletype program. In this
case, I wanted the computer to
insert the time and date when i

ten on the subject. The salient
difference between this pro-
gram and many of the others
lies in the format in which the
time is stored. Most programs
store the time in packed BCD
form.

At first, you might think that
this is an efficient manner in
which to store the time, for it re-
quires very little memory. How-
ever, the disadvantage is that
several other routines are re-
quired to retrieve the time, and
print is in a form that can be
read on paper. For example, the
packed BCD digits must be sep-
arated, converted to ASCII, and
then colons, spaces, slashes
and perhaps a carriage return
and line feed must be added to
give the necessary readable out-
put format.

The format used in this pro-
gram has all the necessary char-
acters and commands, and all
you have to do is access the
string of continuous addresses
whenever the time and date are
required. In essence, this format
is a sentence that can be ap-
pended to virtually any event (for
example, 12:17:36 06/21/79).

A second characteristic of

Fig. 1. The timebase for the software real-time clock can be derived
from the commercial power line timebase of 60 Hz. The program al-
lows virtually any other frequency to be used as well.

typed a particular control char-
acter. This article is the result of
my labors and should prove use-
ful to others, for it is, in some
ways, a unique real-time clock
program.

Program Description

Three characteristics of the
program make it unique from
many of the other articles writ-

this program is that it contains
the month, day and year infor-
mation, which most other pro-
grams lack. This is a particularly
important feature for a security
system or any other continuous-
ly run system. Only during a leap
year or a new decade is there a
need for human intervention.
However, it’s obvious that a lit-
tle extra programming could ob-

1 50 Microcomputing January 1980

viate this requirement.

The third difference is the way
in which the time is initialized.
Most other programs that I have
seen require the user to access
particular memory locations
and insert the time and date in
packed BCD form employing the
user’s operating system.

The method used in this pro-
gram is far simpler and quicker.
All the necessary prompts are
given so that there is little
chance for error. For example,
the time indicated above could
have been initialized by the fol-
lowing:

HR 4612
MIN 517
SEC 36
MO 06
DAY 21
YR 7879

When the program begins, the
computer will respond by print-
ing the HR prompt on the termi-
nal, at which time the operator
inserts the hour desired. If you
make an error, merely continue
by inserting the correct hour.
The program has been written to
accept only the last two digits.
For example, in the above exam-
ple, 12 hours rather than 46 will
be the starting time. Likewise,
the number of minutes will be
17, and the year 79.

When the correct digits have
been inserted after a particular
prompt, a carriage return will
bring up the next prompt. The
program has been written so
that only valid ASCII numbers
will be accepted, in other words,
alpha or control characters will
not be inserted or echoed back
to the terminal. The carriage re-
turn after the YR prompt will
clear the interrupt mask bit,
which was set upon entrance in-
to the program, and the MPU will
begin servicing interrupts.

Therefore, the time can be ini-
tialized, and when that moment
actually occurs, a carriage re-
turn command will synchronize
the program with the real time.
Since an IRQ interrupt, rather
than an NMI interrupt, is used,
there is no need to inhibit pulses
during the loading or initializa-
tion of the program.

Finally, the program does not
make any calls to the user’s op-
erating system subroutines
such as MIKBUG’s OUT2HS or
PDATA1. For this reason, the

program is independent of the
user’s operating system, and,
therefore, it should be compati-
ble with virtually any system us-
ing the 6800.

With initialization complete,
the program branches to the
CHRIN subroutine, which waits
for a character from the termi-
nal. If the character is a T, the
time and date sentence is print-
ed. This is the clock demon-
stration routine and is included
for testing purposes. When the
user is satisfied with the opera-

tion of the program, control
should be transferred to the us-
er’s main program rather than
the clock demonstration rou-
tine, which begins at $0869.

Hardware

Before you implement a real-
time clock, you should first de-
termine whether it will be a hard-
ware or software clock. Each
has its advantages and disad-
vantages. Briefly, the salient ad-
vantage of the software clock is
the cost. Since there is virtually

no hardware required, there is
essentially no cost involved. On
the other hand, a software clock
does require more memory than
a hardware clock, and it typical-
ly uses more of the computer’s
time. This impediment is so
slight as to be nonexistent
(more on this later).

The hardware clock is more
advantageous when the com-
puter is not run continuously,
since loading and initialization
are not required each time the
computer is turned on. Since my

Fig. 2. Flowchart for the main portion of the program shown in listing 3. This, together with the com-
ments in the listings, should allow non-6800 owners to design a similar program. Note that ail variables
are in ASCII and that, basically, the program checks for an overflow condition of the variables. For exam-
ple, if units of seconds overflows from 9($39) to :($3A), there will then be a need to reset units of seconds
back to 0($30) and increment tens of seconds and check for an overflow of 6($36).

Microcomputing January 1980 151

security system computer is on
continuously, the advantages of
the software clock outweighed
the disadvantages.

After deciding on a software
clock, you must ask if the non-
maskable interrupt (NMI) or the

interrupt request (IRQ) line of
the 6800 should be used. Once
again, each method has advan-
tages and disadvantages.

The NMI interface method
does not require an additional
1C, such as a peripheral inter-

face adapter (PIA), since it inter-
faces directly to the 6800. How-
ever, this method can cause
problems in some applications.
For example, if an ongoing pro-
gram uses the MPU for timing
loops, the accuracy of the tim-

ing loop will be impaired due to
the overhead time of the clock
program.

A second deficiency of this
method lies in the fact that there
must be a means of disabling
the interrupts (i.e., a switch) until
the program is loaded. This can
be partially overcome by burn-
ing the program into ROM, but
then other problems arise since
the NMI vectored address must
also be in nonvolatile memory.
While this is certainly possible,
the flexibility of the computer
system would be slightly im-
paired. Finally, a typical system
has several IRQ inputs, but only
one NMI input. Therefore, the
NMI cannot be used for other
purposes.

For these reasons, I used a
“soft” interrupt (IRQ) via a PIA.
More specifically, as shown in
Fig. 1, the interrupts were inter-
faced via the CB1 control line of
the PIA. The data register of the
B port of this PIA is at $8101, and
the control register is at $8109.
Of course, any PIA can be used
with the necessary addresses
altered in the program. The pro-
gram assumes that the sys-
tem’s terminal is interfaced to
the MPU via an ACIA with con-
trol and status register at $8300,
and the data register at $8301.

The timebase for the inter-
rupts is derived from conven-
tional 60 Hz commercial power.
While virtually any timebase can
be used, this timebase source
has the advantage that it is ac-
curate, reliable and readily avail-
able. Fig. 1 gives the details of
the timebase circuit. A 12 V ac
transformer is indicated, but a
standard 6.3 V ac filament trans-
former should prove equally ac-
ceptable. The 7414 is a Schmitt
trigger inverter, which provides
the necessary hysteresis to pre-
vent false interrupts due to
power-line fluctuations.

The output of the circuit is a
clean, TTL-compatible signal at
a 60 Hz repetition rate. The soft-
ware provides the necessary di-
viding to give a 1 Hz timebase
for seconds. Note that the com-
puter system will be more effi-
cient with a lower interrupt rate.
For example, assuming a 1 MHz
MPU clock frequency, each time
an interrupt occurs, approxi-
mately 100 microseconds are

0850

ORG

t850

0850

OF

BEGIN

SFI

0851

CF

0900

L0X

•START

0854

EF

A000

STX

IRQ

iRO Interrupt vectored address

0857

4F

CLRA

0858

37

0800

ST AA

ktimf

INTIALIZE 60 HZ INTERRUPT COUNTER

085B

37

8109

ST AA

PIAOCB

GET DDR

085E

97

8101

ST AA

PIAOOB

8 PORT OF PIA ALL INPUTS

0881

86

05

LDA A

• 5

0883

97

8109

STAA

PIAOCB

ENABLE CBi INTERRUPT

0886

80

0E

9BR

INITIM

GO INITIALIZE TIME

0868

OF

CLI

0869

80

65

again

BSR

CNR In

go watt For character from tty

286B

81

54

CMP A

*'T

IS IT A RFOJEST for TIMf CHARACTER

0860

26

FA

BnE

AGAIN

BRANCH IF NOT A REQUEST FOR TIME

086F

CE

0822

LDX

• DT

gft ready to print time

0872

80

43

BSR

COX

go prtnt time

0874

20

F3

BRA

AGAIN

continue WAITING FOR COMMAND to print time

0876

80

6 A

INTTIM

BSR

CRLF

PRINT CR AND 1 F

0878

CF

0804

LOX

• NR

GFT PRESENT WORD TO PRINT

087B

80

3A

BSR

COX

PRINT CNR. IN INDEX REG. UNTII *

087D

CE

0824

LDX

• TNRS

starting location to put characters

0880

80

5 A

BSR

timein

GO GET CHARACTERS

0882

CF

0809

LOX

• MIN

gft present word to print

0885

8D

30

BSR

COX

PRINT ChR. IN INDEX REG. UNTIL *

0887

CF

0827

LDX

• TMIn

starting location to put characters

088A

80

50

BSR

TIMEIN

GO GET CHARACTERS

088C

CE

080E

LOX

• SEC

gft Present word to print

088F

80

26

BSR

COX

prtnt ChR. in INDEX REG. UNTIL *

0891

CF

082A

LOX

• TSEC

starting location to put characters

0894

80

46

BSR

timein

GO GET CHARACTFRS

0896

CF

0813

LOX

• MO

gft present word to print

0899

80

1C

BSR

COX

PRINT CHR. IN INDEX REG. UNTIL *

089B

CF

0831

LOX

•tmon

starting location to put characters

089E

80

3C

BSR

TIMEIN

GO GET CMARACTFRS

08 A0

CF

0818

LOX

• DAY

get present word to print

08 A3

80

12

BSR

COX

PRINT ChR. in index REG. UNTIL #

08A5

CE

0834

LOX

•tday

starting location to put characters

08A8

8D

32

BSR

TIMEIN

GO GET CHARACTFRS

08 AA

CE

0810

LOX

• YR

gft present word to print

08 AD

8D

08

BSR

cox

PRINT CHR. in INDEX REG. UNTIL *

08 AF

CE

0837

LOX

• TYRS

STARTING LOCATION TO »UT CHARACTERS

08B2

80

28

BSR

TIMEIN

GO GET CHARACTFRS

0804

7F

09C4

JMP

mtest

set overflow to month

08B7

A6

00

COX

LOAA

0 j X

GFT charactfr to print

0889

81

2A

CmPa

***

IS IT END ,•

08BB

27

05

BfQ

end

IF END. RETURN

08BD

80

04

BSR

CO

IF NOT END. PRINT CHARACTERS

083F

08

INX

08C0

20

F5

BRA

cox

GO GET ANOTHER CHARACTER

08C2

39

END

RTS

RETURN

08C3

36

CO

psha

08C4

96

8300

C01

LOAA

CIOS

is acta ready

08C7

85

02

BTTA

• 2

08C9

9 7

F 9

BFQ

C01

08CB

3?

PULA

rftrifve digit

08CC

97

8301

STAA

CI00

08CF

39

RTS

0800

36

8300

CNR T N

LOAA

CIOS

HAS A CHARACTER COME IN

0803

*7

ASRA

0804

24

Fa

3CC

CNR In

CONTINUE IF ACIA HAS NO CHARACTER

0806

96

8301

LOAA

cioo

gft Character from acia (ttyj

0809

84

7F

ANDA

••7F

08DB

39

RTS

oaoc

8D

F2

timein

BSR

CHRIN

GO GET A CHARACTER FROM TTY

08DE

81

00

CMPA

••OD

IS IT CR

08E0

26

09

BNE

NUMBER

CONTlNUF IF NOT A CR

08E2

86

0A

crlf

LOAA

• •OA

ROUTINE TO PRTNT CR AND LF

08E4

80

DD

BSR

CO

PRTNT LF

0806

86

00

LOAA

••OD

08E8

80

09

B9R

CO

PRTNT CR

05EA

39

RTS

RETURN IF IT IS A SPACE

08EB

36

number

PSHA

SAVE CHARACTER

osrc

84

FO

ANDA

••FO

FORCE LOW ORDFR NIBBLE TO ZERO

08EE

88

30

EORA

••30

IS Hl rt H order nibble 3

08 Fo

27

03

beq

AHEAD

BRANCH IF CHARACTER is AN ASCII NUMBER

0gF2

3?

PULA

it is not an ascii number

08F3

20

E7

BrA

TIMEIN

CONTINUE WAITING FOR a NUMBER

08F5

A6

01

AHEAD

LOAA

liX

get other digit

oar7

A7

00

STAA

OiX

store digit at next location

08F9

32

PULA

retrieve nfw digit

08FA

A7

01

Staa

liX

store new digit

08FC

80

C5

BSR

CO

PRINT NEW DIGIT

08FE

20

DC

BRA

TIMEIN

Listing 2. Initialization portion of the program ($0850) where the program begins. This routine gives
the operator the necessary prompts to insert the hours, seconds, minutes, etc. With the initialization
complete, interrupts are enabled and the program waits for a “T” from the keyboard, at which time
the time and date sentence is printed. This portion of the program may be removed.

152 Microcomputing January 1980

used by the software clock rou-
tine. Thus, during a one-second
period, the computer is called
upon for 6 ms (.6 percent) to ser-
vice the clock program. If you
add an external hardware divid-
ing circuit, such as a divide by 60
(i.e., Motorola MCI 4566) to give
an interrupt only once a second,
the 6 ms of overhead time will be
reduced to 100 microseconds
(.01 percent).

You can decide for yourself if
the reduction in time is worth
the extra effort of adding addi-
tional hardware. Bear in mind
that the 100 microseconds of
overhead time discussed above
is an average. The worst case is
approximately 400 microsec-
onds, which occurs at the end of
the year when all the variables
roll over.

Software

The flowchart (Fig. 2) and the
comments in the listings should
be enough to give an explana-
tion of the workings of the pro-
gram. There are, however, a few
points worthy of further clarifi-
cation. When an interrupt oc-
curs, the current status of the
MPU is saved on the stack. The
MPU then jumps to the location
stored in location $FFF8 and
$FFF9. In most systems using
the 6800, this information is in
nonvolatile memory. Therefore,
the MPU is directed to another
address in volatile memory, usu-
ally $A000 and $A001.

The second and third Instruc-
tions in the program shown in
Listing 2 show how $A000 and
$A001 are initialized. In a system
using multiple interrupts, the us-
er will wish to alter this address
to allow control to be trans-
ferred to an interrupt polling
subroutine, which determines
the origin of the interrupt.

As shown in Listing 1, the
time and date sentence starts at
location $0822 and ends at
$083C. The last character is an
asterisk (*), which is used as the
end of transmission character.
The subroutine COX prints the
characters until it detects the
asterisk and then returns. The
number of spaces between the
time and date, as well as the en-
tire format of the sentence, may
be altered, but this may require
that the program be reas-

Li sting 3. Heart of the software clock (see Fig. 2). Each time an interrupt occurs, the MPU is vectored
to location START ($0900). If 60 interrupts have not occurred, the MPU will immediately return from
the interrupt. However, if 60 interrupts have been counted, execution will continue and the time and
date will be updated as necessary. If a timebase other than 60 Hz is used, merely change the operand
of the CM PA instruction at location $0909.

0900

86

8101

•

ST4RT

LDA4

PIA0DB

CLEAR INTERRUPT FRBM PIA

0903

7C

0800

INC

KTIME

ADO BNE TS INTERRUPT CBUNTFR

0906

86

0800

L0AA

ktime

0909

81

3C

CMP4

#60

WATT F8R 60 INTERRUPTS

0908

27

01

BFQ

CLOCK

IF 60 INTFRRUPTS PASSED GO T8 CL®CK PROGRAM

0900

3B

RTI

09 0E

7F

0800

CLOCK

clr

KTIMC

0911

C6

30

LDAB

#930

0913

7C

0823

INC

usee

ADD BnE TB JNTT SECONDS

0916

36

0823

L0A4

USEC

LOAD ACC A WITH UNIT SECONDS

0919

88

34

E0RA

#93 A

0918

27

01

BFQ

ITSEC

UNIT SECONDS OVERFLOW* 3B INC T SECS

0910

38

RTI

091 E

7C

0824

ITSFC

INC

TSEC

INCREMENT TCN9 BF SEC8N0S

092 1

F7

0828

STAB

USEC

0924

86

082a

LDA4

TSEC

0927

88

36

EftRA

#936

0929

27

01

BFQ

IUMIN

tens bf seconds overflow* inc u min

092B

38

RTI

09?C

7C

0828

IUMIN

INC

UMIN

increment UNIT minutes

09?F

F7

0824

STAB

TSEC

0932

86

0828

L0AA

UMIN

0935

88

34

E8RA

#t3A

0937

27

01

BFQ

ITMIN

UNITS MINUTES OVERFLOW* INC T MIN

0939

3B

RTI

093 A

7C

0827

ITMTN

INC

TMIN

increment TENS 0F minutes

0930

F7

0828

STAB

UMIN

0940

36

0827

LDAA

TMIN

0943

88

36

EBRA

#936

0945

27

01

beq

IUHRS

tens of mtnutfs overflow* inc u hrs

0947

3B

RTI

0948

7C

0825

IUHRS

INC

UHRS

INCREMENT UNIT HOURS

0948

P7

0827

Stab

TMIN

09aE

86

0825

LDA4

UHRS

0951

81

34

CMPA

#934

0953

27

OC

BFQ

ISIT?

0955

81

3A

Cmpa

#93 A

0957

27

01

beq

ITHRS

UNIT hours BVrRFLBW# INC T BF HRS

0959

98

RTI

095A

7C

0824

ITHRS

INC

THRS

INCREMENT tens of hours

0950

F7

0825

STAB

UHRS

0960

38

RTI

0961

B6

0824

iSIT?

LDAA

THRS

0964

81

32

CMPA

#932

0966

27

01

BEQ

IUDAY

TENS OF HOURS OVERFLOW* INC U DAY

0968

38

RTI

0969

7C

0835

IU04Y

INC

U0AY

INCREMENT UNIT BF DAYS

096C

F7

0824

STAB

THRS

096F

F7

0825

STA3

UHRS

0972

86

0835

LDAA

UDAY

LOAD ACC A WITH UNIT DAY

0975

B 1

0801

CMPA

UDAYt

DOES UNIT DAY INDICATE END OF MONTH

0978

27

OC

BCQ

I S I T 3

BRANCH* UNITS OF DAY INDICATES END OF MONTH

097A

81

3A

CMPA

#93 A

097C

27

01

BCQ

itday

tens of Days overflow

097E

38

RTI

097F

7C

0834

IT04Y

INC

TDAY

0982

F7

0835

STAB

UDAY

RE6ET UDAy TO 0

0985

3B

RTI

0986

86

0834

1SIT3

loaa

TDAY

LOAD ACC A WITH TDAY

0989

B1

0802

CMPA

TDAYi

DOFS TEN OF DAY INDICATE END OF MONTH

098C

27

01

BFQ

NFWMS

nfw month

098E

3B

RTI

098F

7C

0832

NEWM0

INC

UMBN

0992

F7

0835

STAB

UDAY

reset day to the beginning bf month

0995

7C

0835

INC

UDAY

0998

F7

0834

stab

TDAY

Reset Day to beginning of month

0998

36

0832

LOAA

UMBN

099E

81

33

CMPA

#933

DOES UNITS of month INDICATE END BF YEAR

09A0

27

00

BFQ

ISIT4

0942

81

34

CMPA

#93 A

0944

26

06

BNE

CBNT1

0946

7C

0831

INC

TMBN

0949

27

083?

STAB

UMBN

094C

3D

16

CONTI

BSR

MTEST

what is thf number of days in new month

094E

9B

RTI

094F

86

0831

ISIT4

LDAA

tmbn

0982

81

31

CMPA

#931

0984

26

F 6

BNE

CBNTl

0986

7C

0838

INC

UYRS

increment unit of years

0989

F7

0832

STAB

UMBN

RESET TO FIRST MONTH OF NEW YEAR

C9BC

7C

0832

INC

UMBN

09BF

F7

0831

Stab

tmbn

REST to First month of new year

09C2

20

E8

BRA

CBNTl

•

F8RM 2

PACKED BCD

DIGITS FROM UNIT6 of mo. and tens of MO.

09C4

36

0831

MTEST

LDAA

TMgN

09C7

P6

083?

LDAB

UMBN

09CA

C4

OF

AN0B

#90F

Set Bits 4#5*6* and 7 to zero

09CC

F7

0809

STAB

UMBNl

09CF

48

A8LA

0900

48

A8LA

09D1

48

ASLA

09D2

48

ASLA

0903

34

0809

OR AA

UMBNi

0906

81

03

FEB

CMPA

#2

0908

26

02

BNE

APRIL

0904

20

21

BRA

M928

SET TO MONTH WITH 28 DAYS

09DC

81

04

APRIL

Cmpa

#4

090E

26

02

BNE

JUNE

09E0

20

26

BRA

M830

SET TO MONTH WITH 30 DAYS

09F2

81

06

JUNE

CMPA

#6

09£4

26

02

BnE

sept

09E6

20

20

BRA

MB30

SET TO MONTH WITH 30 DAYS

09F8

81

09

SEPT

CMPA

#9

09F4

26

02

BNE

N8V

09EC

20

14

BRA

M830

SET TO MONTH WITH 30 DAYS

09EE

81

11

NOV

Cmpa

#91 1

09F0

27

16

BFQ

M830

Microcomputing January 1980 153

09F2

86 32

MB31

LDAA

• • 38

09F4

B7 0801

STAA

UDAYl

09F7

86 33

LDAA

«t33

09F9

87 0802

STAA

TDAYl

09FC

39

RTS

09FD

86 39

M828

LDAA

#•39

09FF

B7 0801

STAA

UOAYi

0A02

86 32

LDAA

••32

0A04

B7 0802

STAA

TDAYl

0A07

39

*

RTS

0A08

86 31

•

M830

LDAA

••31

0 AO A

B 7 0801

STAA

UDAYl

0A00

86 33

LDAA

•*33

OAOF

B7 0802

STAA

TDAYi

0A12

39

RTS

0A13

END

if THfRc rs no match# it must be a mbnth
htth ji Day#

MBigTHf THAT have 31 DAYS ABE

JAW# MARCH. MAY# JULY# AUQ# BCT# DEC

February

MBWTHg THAT Have 30 DAYS ARE
APRIL. JUNE * SEPT. NOV

sembled, depending on the na- As previously stated, the in- changed to virtually any value,
ture of the change. terrupt frequency can be For example, if the 60 Hz time-

base is reduced to 15 Hz, simply
change the operand value of the
CMP A instruction at $0909 from
60 ($3C) to 15 ($0F).

The program requires slightly
over 1/2K of memory, and execu-
tion starts at $0850. Reassem-
bling the program at $0000
would improve the efficiency,
since the 6800 could then use
direct addressing. This has an
advantage since it would de-
crease the program’s overhead
time, as well as reduce the
amount of memory required. ■

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* Requires only 2 I/O ports to interface to your microcomputer.

* On board voltage regulators.

* Supplied with connector, sockets for IC's.

* Ready to use when you receive it.

* 10 Meg input impedance (A/D), latched D/A converters.

* Packaged on 4.25"x3.75" PC card.

* 8 bit accuracy for A/D and D/A.

* Gold plated PC board contacts.

* Address decode for A/D.

* Assembled and tested, price $115.00.

The ANALOG I/O 802 is easily interfaced to microcomputer I/O
ports including: the 6820, 6520, 6530, 6522, 3850, 3851, 8755, 8212,
etc.

Optimal Technology, Inc.

Blue Wood 127, Earlysville, VA 22936

Phone (804) 973-5402 ^ 01 °

BASF
6106

5.25 f

FLOPPY DISK
DRIVE

• 40 Track, single or double
density

• Smaller size. Fit 3, 6106
drives into the space of 2
SA 400 drives

• Track to track access
time: 12 MSEC.

• Requires less power,
generates less heat

• Uses ball bearing friction-
free head positioner

• Uses industry standard
interface and power
plugs, and mounting
points.

ALL THE ABOVE FEATURES AND MORE FOR ONLY

$299.00 ea.

FOR MORE INFORMATION CONTACT:

OTTO ELECTRONICS

P.O. BOX 3066, PRINCETON, NJ 08540
^ 09 or call 609-448-91 65

MC, VISA, COD accepted. NJ residents add 5% sales tax. Shipping and insurance extra.

Reader Service— see page 227

Microcomputing January 1980 155

YOU MAY ALREADY OWN

YOUR NEXT 1200 BAUD DECWRITER"

UPGRADE YOUR LA36 TO STATE-OF-THE-ART
PERFORMANCE WITH THE DS120 TERMINAL CONTROLLER

FASTER— The DS120 prints at up to 165 cps and maintains true 1200 baud throughput This translates into lower costs in
computer time as well as time savings for you. A 1000 character internal print buffer virtually eliminates the need for fill
characters.

SMARTER— Our microprocessor control intelligently" optimizes carriage movement by printing bidirectionally and auto-
matically executing high speed tabs over any blank spaces in the text

MORE VERSATILE— We offer more standard features than any 1200 baud teleprinter currently available A complete list of
forms control and formatting features are programmable from the keyboard or via the data stream. The DS120 is
equipped with both an EIA RS232-C interface and a 20 mA Current Loop interface. The unit communicates using the 1 28
character ASCII set at baud rates from 1 10 to 4800 Full-duplex, half -duplex and echo-plex modes may be selected from
the keyboard. The controller supports half-duplex transmission using both coded-character turn around and reverse
channel protocol.

EASY TO INSTALL, EASY TO USE— The DS 1 20 replaces your LA36 logic card in a matter of minutes and is fully compatible
with the existing electronics. A comprehensive User s Manual provides detailed instructions for installation and
operation

RELIABLE— Our performance and reliability have been field proven in over 2500 installations.

INEXPENSIVE — BUT NOT CHEAP - Although the DS120 is just about the lowest cost way to print at 1200 baud, we don t
cut corners on quality. The DS120 is built for years of service using pretested, high reliability components from leading
manufacturers. Each unit undergoes a 48 hour test cycle before shipment and carries a 90 day warranty on materials and
workmanship

AVAILABLE - We can deliver typically within 30 days after receiving your order Our stocking distributors are con-
veniently located in major cities throughout the U.S. for even better delivery

DATASOUTH COMPUTER CORPORATION

627-F Minuet Lane*Charlotte, North Carolina 28210* 704/523-8500

DECWRITER* is a rogislorarj badamartt ol Ojilai Fquipnwvi Corporation installation ol the DS 120 w* void any OEC warranty or service contract

TRS-80® BUSINESS SOFTWARE

Why not buy THE GENUINE ARTICLE???

The Osborne & Associates applications (Payroll with Cost Accounting, Accounts Pay-
able & Accounts Receivable, and General Ledger) are on their way to becoming the
standard applications software in the microcomputer field.

The genuine O&A software is written in CBASIC® for the CP/M® Operating System.
Any other combination of language and operating system represents a reprogramming
effort. . .for the TRS-80, Model 1, several organizations have done such a reprogram-
ming in Disk BASIC under TRSDOS. These packages have certain drawbacks such as
having some features of the application removed. In addition, the fact that they are writ-
ten in a source interpreter BASIC causes the comments in the source programs (if these
are distributed at all) to be removed in the interest of saving space and execution time.
Since CBASIC is a compiled language, comments cost nothing (in either space or execu-
tion time) in the executable version of the file — but such comments are invaluable in the
later program maintenance and modification that is always required on applications soft-
ware. Without having such comments, it is easy to spend many times the cost of the soft-
ware on just one modification/maintenance effort. A buyer should take this into con-
sideration when looking at the apparent cost of the package. The CBASIC source pro-
grams we sell are heavily commented to aid the programmer.

Our programs are THE GENUINE ARTICLE. . .the CBASIC source code as de-
veloped by Osborne & Associates. We furnish the buyer BOTH the TRS-80, Model I ver-
sion (requires a 48K Model I with two or more disks) AND the unmodified 8” version (for
later use on the TRS-80, Model II or other 8” CP/M system). . .at no extra charge. By
using our DOWNLOAD program, it is possible to start using the applications on the
Model I, and then when the Model II is up and running at a later date, download the data
files from the Model I to the Model II and keep running the same applications without
disrupting your operation.

The Osborne & Associates books have been rewritten to reflect the CP/M, CBASIC
versions of the applications. These books can be purchased either from your local
computer store or from us directly. We can see no percentage in your buying other than
THE GENUINE ARTICLE. . .which is what we sell. . .the Osborne & Associates
source programs in CP/M and CBASIC.

CP/M Operating System $ 1 50.00

CBASIC Compiler 95.00

O&A Payroll w/Cost Accounting 250.00

uoa accis. Kec./Accts. rayaDie

O&A General Ledger w/Cash Journal . 250.00

O&A CBASIC books for above (each) 1 5.00

DOWNLOAD program 95.00

TRS-80 is a registered trademark of Radio Shack, a Tandy company
CP/M is a registered trademark of Digital Research
CBASIC is a registered trademark of Software Systems

tS C129

1C V B E R N E T I C S
1C

804 1 NEWMAN AVENUE • SUITE 208 • HUNTINGTON BEACH. CALIFORNIA 92647 • (714)848-1922

Adventure

^International j0p|>

“Highest rated games are the Adventure games".

Robert Purser Edition 7 CCR

Declared a true “Classic".

Computer Cassettes Review, Fall 79

"Adams' Adventure is exquisite. It is a true
tour-de-force . .

Recreational Computing Sep/Oct 79

Out of 50 programs reviewed Adventure was
rated No. 1! "Highly Recommended".

80 Software Critique Issue No. 7

"I highly recommend these programs”-

80- US Journal, Sept /Oct 79
Adventures by Scott Adams are available from
our many fine Dealers for TRS-80, Pet, Sorcerer
and by Christmas, the Apple II!

Write for free flyer — Each Adventure $14.95

Adventure International ;xA102
Box 3435

Longwood, Florida 32750
COD/Visa/Mastercharge — Call (305) 862-6917

r

-\

TRS-80 COMPUTING

nonprofit newsletter

12 Issues For $15.00

and now

PEOPLE’S SOFTWARE

at popular prices

•Tape 1: 34 Level II or 24 Level I (indicate which you
want) business, home, educational. $7.50
•Tape 2: 77 Level II from “Common Basic Programs”
by Osborne Associates. $7.50
•Tape 3: People’s Pascal program development sys-
tem. $15

•Tape 4: 21 misc. Level I programs. $7.50
•Tape 5: 24 misc. Level II programs. $7.50
•Tape 6: People’s Pascal II. $23.00

Add 50$ P&H each tape, CA residents add tax.

t>C104

COMPUTER
INFORMATION
EXCHANGE

Box 158 San Luis Rey, CA 92068

J

TRS-80 SOFTWARE

MONITOR #3 $39.95

Disassembler; ASCII and hex displays; memory move,
search, verify, and modify; read and write object tapes;
hex arithmetic; object code relocates unload programs
from TRSDOS memory areas to disk; symbolic tape.

MONITOR #4 $49.95

Adds: save and read disk files; direct input and output of
disk sectors; send, receive or talk to another computer
via the RS-232-C Interface; symbolic disassembly on disk.

PACK/UNPACK $24.95

increase disk file capacity by 33% with NO NEW HARD-
jWARE. Applies only to string data. Ideal for mailing lists,
^telephone files, etc.

HOME BUDGET $49.95

Keeps track of your checkbook, income, and monthly
bills. Computes monthly and year-to-date summaries.
'(Requires 32K, disk.)

MAILING LIST $69.95

Over 1000 names on a single diskette! Add, change,
delete, find name, alphabetic or zip sort, print labels or
master list. (Requires 32K, disk.)

HOWE SOFTWARE

14 Lexington Road ^ H47
New City, NY 10956

156 Microcomputing January 1980

New from NRI!

The First Interdisciplinary
Home Study Course Ever Offered

As the microprocessor revolutionizes
the computer world and microcomputers appear
almost everywhere, NRI brings you a new, con-
venient, and effective way to keep up with this
expanding technology. It’s NRI’s courses in
Microcomputers and Microprocessors, created
and designed exclusively for learning at home
in your spare time.

Designed for the New Breed
of Computer Technician

It’s no longer enough to be just a pro-
grammer or technician. With microcomputers
moving into the fabric of our lives as low-cost,
easily available tools for business and home,
both the programmer and technician must
become total professionals. With practical
knowledge of hardware, the programmer can
design simpler, more effective programs. And
with advanced programming skills, the tech-
nician can test and debug systems quickly and
easily. The NRI course gives you simultaneous
training in both skills. . .makes you one of this
rare new breed.

Build Microcomputer,

Test Instruments

NRI goes far beyond book learning to give
you practical, “hands-on’’ experience. As you
learn, you actually assemble NRI’s designed-
for-leaming microcomputer. It performs like
the finest of its kind, and features both assembly
and basic language capabilities.

Every assembly step’s a learning step.
Using the NRI Discovery Lab® plus the NRI
transistorized volt-ohm meter and CMOS digital
frequency counter you also build, you perform
meaningful experiments throughout your
course... trace circuitry, interface components,

introduce and correct problems, design your
own programs, and more.

The Proven Way to Learn
at Home

You don’t have to worry with travel, classes,
or time lost from work when you learn the NRI
way. As they have for more than 60 years of teach-
ing technical subjects, NRI brings the material
to you. You study in your spare time, at your
convenience, using “bite-size” lessons that
program material into logical segments for easier
assimilation. You perform experiments and build
equipment using kits we supply. And your per-
sonal NRI instructor is always available for con-
sultation should you have questions or problems.
Over a million students have already shown
the effectiveness of NRI
training.

Choice of
Courses

Several courses
are available, depending
upon your needs and
background. NRI’s
Master Course in Micro-
computers and Micro-
processors starts with
the fundamentals,
explores basic electronics
and digital theory, the
total computer world,
and the microcomputer.

The Advanced Course,
for students already

versed in digital electronics, concentrates on
software and the world of the microprocessor
and microcomputer. In both courses, you build
all instruments and your own computer.

Send for Free Catalog. . .

No Salesman Will Call

Get the details on these exciting new
courses in NRI’s free, 100-page catalog. Shows
all kits and equipment, lesson outlines, and full
information, including facts on other electronics
courses. Mail the coupon today and we’ll rush
your catalog. No salesman will ever call. Keep up
with the latest technology as you learn on your
own computer. If coupon has been removed,
write to NRI Schools, Computer Department,
3939 Wisconsin Ave., Washington, D.C. 20016.

NRI Schools

McGraw-Hill Continuing
Education Center
3939 Wisconsin Avenue
Washington, D.C. 20016

NO SALESMAN WILL CALL

Please check for one free catalog only.

□ Computer Electronics Including
Microcomputers

□ TV/Audio/Video Systems Servicing

□ Complete Communications Electronics
with CB • FCC Licenses • Aircraft,

Mobile, Marine Electronics

□ CB Specialists Course

□ Amateur Radio • Basic and Advanced

All career courses
approved under GI Bill.
□ Check for details.

□ Digital Electronics • Electronic
Technology • Basic Electronics

□ Small Engine Repair

□ Electrical Appliance Servicing

□ Automotive Mechanics

□ Auto Air Conditioning

□ Air Conditioning, Refrigeration, & Heating
Including Solar Technology

(Please Print)

City/State/Zip

Accredited by the Accrediting Commission of the National Home Study Council

172-010

iS Reader Service— see page 227

Microcomputing January 1980 157

The PET® Gazette
and PET User Notes
are now a part of

COMPUTE.

The Journal for Progressive Computing

Continuing major sections on Business, Indus-
trial and Educational Applications and Re-
sources, Plus The PET® Gazette, The ATARI®
Gazette, The APPLE® Gazette and The SBC
(Single Board Computer) Gazette. All in each
issue!

A Sampling of Our 104 page “Super” Fall
Issue:

Tokens in Microsoft BASIC: Harvey
Herman. ATARI Computers: The Ultimate
Teaching Machines?: John Victor. Carl
Moser Presents a Universal 6502 Memory
Test. Microcomputers in Nuclear Instru-
mentation: Joe Byrd. AIM 65 Review: Don
Clem. Mastering The Ohio Scientific Chal-
lenger IP A Learn-By-Doing Approach:
Keith Russell and Dave Shultz. CORVUS
11A Disk Drive for APPLE: A Review by
Michael Tulloch. Pierre Barrette on Micro-
computers in Education. Len Lindsay Re-
views Three Word Processors. PET in Trans-
ition/ROM Upgrade Map: Jim Butterfield.
Trace for the PET: Brett Butler. 32K PET Pro-
grams Arrive: Len Lindsay. Using Direct
Access Files With the Commodore 2040
Dual Disk Drive: Chuck Stuart, plus Re-
views, Resources and Products.

New Features Coming in January include:

"Rambling" by Roy O'Brien and "The Tape
Exchange" by Gene Beals.

1980 Bimonthly Subscription (Six Issues) $ 9.00

"Super" Fall Issue With 1980 Subscription 1.00

$ 10.00

Make Check or Money Order Payable to COMPUTE.

Post Office Box 5119

Greensboro. North Carolina 27403 USA ^ ci 73

COMPUTE., the new
6502 resource magazine for
PET, Apple, Atari, Kim, Sym, Aim
and OSI Owners.

COMPUTE. The Journal for Progressive Computing is pub-
lished by Small System Services, Inc. of Greensboro, North
Carolina. Robert Lock, Editor/ Publisher.

MACO MAGIC MODULE

TRS-80 USERS

Expand your TRS-80 without the need for an
expensive expansion interface with these features:

o Self-Contained Power supply

o Audio Output for Music, Monitroing Cassette, and Signaling
0 Real-Time Clock Displayed Upper Right Screen - HR:MIN:SEC

0 Two Hand Controllers

0 Software Package: Comput-A-Sketch Micro-Organ

Brickyard Real-Time Clock

o Instructions For Use With Basic And Assembly Language

MaCo Manufacturing
1383 Airways Boulevard ^ M124
Memphis, TN 38114

ORDERING: Money Order or Check - We Pay Freight

Visa, Master Charge, C.O.D. - Freight will be added to the order.

On charge cards include all data on cards as well as complete address.

16 K STATIC RAM

with

$275 450 ns

$300 250 ns

memory chips

Assembled, Tested and Guaranteed

Static TMS 4044 or equivalent - Fully Static 4Kx1 Memory Chips
for full DMA capability, no tricky timing problems.

Fully S-100 Bus Compatible - All lines fully buffered, Dip Switch
Addressable in two 8 K block, 4K increments. Write Protectable
in 2 blocks, Memory Disable using Phantom, Battery back up
capability.

Bank Select - Using output port 40H (Cromemco software
compatiblej-addressable to 512KB of Ram for time share or
Memory Overlap, also has alternate ports 80 H, COH.

Guaranteed - Parts and labor for one year. You may return the
undamaged board within 10 days for a full refund.

Orders - You may phone for Visa, MC, COD ($4 handling charges
for COD) orders. Personal checks must clear prior to shipping.
Shipping-Stock to 72 hours normally. Will notify expected
shipping date for delay beyond this. Illinois residents add 5%
tax. Please include phone number with order.

*>S129

S f CTnirrii-at P-O.Box 906 Phone:

-LUgllal Aurora, I L 60507 (312)897-7749

158 Microcomputing January 1980

jtadjgjhagjt DIALER
COMPUTER CENTER

IWCRQ WflWflGElYIEWT

SVSTEITIS

is M95

Up To 15% Discount
on

TRS-80's

MICRO COMPUTER SPECIALIST

LARRY OWENS

COMPUTER CENTER

MINIMALL-DOWNTOWN SHOPPING CENTER
115C Second Ave. S.W.

Cairo, Georgia 31728
912-377-7120

TRS-80

Your TRS-80 II 16K
is the life of the party with

PARTY PROGRAM

PARTY PROGRAM is the perfect
excuse to show off your computer.
PARTY PROGRAM offers your fav-
orite drinks, fun, graphics & a barrel
of laughs.

- An excellent Christmas Gift - or
“Anytime Gift” for the computer nut
in your world.

Only Si 4. 95 for cassette

For same day service call
( 715 ) 234-2680

Use your Visa or Master Charge

S<fKexyC<tficd

iS N29

Box 336 Route 4
Rice Lake, Wis. 54868

SIMUTEK PRESENTS

★ TRS-80 ★

GAMES

!!! WHOLESALE!!!

************** PACKAGE ONE **************

GRAPHIC-TREK “2000" - This full graphics, real time game is full of fast, exciting action! Exploding
photon torpedoes and phasers fill the screen! You must actually navigate the enterprise to dock with the
giant space stations as well as to avoid klingon torpedoes! Has shields, galactic memory readout, damage
reports, long range sensors, etc! Has 3 levels for beginning, average, or expert players! * INVASION
WORG Time: 3099, Place: Earth's Solar System Mission: As general of Earth's forces, your job is to
stop the Worg invasion and destroy their outposts on Mars, Venus, Saturn, Neptune, etc! Earth's Forces:
Androids — Space Fighters — Lazcr Cannon — Neutrino Blasters! Worg Forces: Robots Saucers —
Disintegrators — Proton Destroyers! Multi level game lets you advance to a more complicated game as you
get better! * STAR WARS — Manuever your space fighter deep into the nucleus of the Death Star! Drop
your bomb, then escape via the only exit. This graphics game is really fun! May the Force be with
you! * SPACE TARGET — Shoot at enemy Ships with your missiles. If they eject in a parachute,
capture them — or if you're cruel, destroy them! Full graphics, real time game! * SAUCERS — This fast
action graphics game has a time limit! Can you be the commander to win the distinguished crossl
Requires split second timing to win! Watch out!

* * * *

* PACKAGE TWO *************

CHECKERS 2.1 — Finally! A checkers program that will challenge everyone! Expert as well as amateur!
Uses 3-ply tree search to find best possible move. Picks randomly between equal moves to assure you of
never having identical games. * POKER FACE — The computer uses psychology as well as logic to try
and beat you at poker. Cards are displayed using TRS-80's full graphics. Computer raises, calls, and
sometimes even folds! Great practice for your Saturday night poker match! (Plays 5 card
draw). * PSYCHIC — Tell the computer a little about yourself and he'll predict things about you, you
won't believe! A real mind bender! Great amusement for parties. * TANGLE MANIA — Try and force
your opponent into an immobile position. But watch out, they’re doing the same to you! This graphics
game Is for 2 people and has been used to end stupid arguments. (And occasionally starts
them!) * WORD SCRAMBLE — This game is for two or more people. One person inputs a word to the
computer while the others look away. The computer scrambles the word, then keeps track of wrong
guesses.

* * * * PACKAGE THREE ***********

POETRY This program lets you choose the subject as well as the mood of the poem you want. You
give TRS-80 certain nouns or names, then the mood, and it does the rest! It has a 1000-word + vocabulary
of nouns, verbs, adjectives and adverbs! * ELECTRIC ARTIST — Manual: draw, erase, move as well as,
Auto: draw, erase and move. Uses graphics bits not bytes. Saves drawing on tape or disk! * GALACTIC
BATTLE The Swlneus enemy have long range phasers but cannot travel at warp speed! You can, but
only have short range phasers! Can you blitzkrieg the enemy without getting destroyed! Full graphics —
real time! * WORO MANIA Can you guess the computer's words using your human intuitive and
logical abilities? You’ll need to, to beat the computer! * AIR COMMAND — Battle the Kamikaze pilots.
Requires split second timing. This is a FAST action arcade game.

* * * *

* * *

* * * *PACKAGE FOUR *************

LIFE — This Z-80 machine language program uses full graphics! Over 100 generations per minute make it
truly animated! You make your starting pattern, the computer does the rest! Program can be stopped and
changes made! Watch it grow! * SPACE LANOER — This full graphics simulator lets you pick what
planet, asteroid or moon you wish to land on! Has 3 skill levels that make It fun for everyone. * GREED
II — Multi-level game is fun and challenging! Beat the computer at this dice game using your knowledge of
odds and luck! Computer keeps track of his winnings and yours. Quick fast action. This game is not
easy! * THE PHARAOH — Rule the ancient city of Alexandria! Buy or sell land. Keep your people from
revolting! Stop the rampaging rats. Requires a true political personality to become good! * ROBOT
HUNTER A group of renegade robots have escaped and are spotted in an old ghost town on Mars! Your
job as “Robot Hunter" is to destroy the pirate machines before they kill any more settlers! Exciting!
Challenging! Full graphics!

► PACKAGE FIVE **************

SUPER HORSERACE Make your bets just like at the real racetrack! 8 horses race in this spectacular
graphic display! Up to 9 people can play! Uses real odds but has that element of chance you see In real
life! Keeps track of everyone’s winnings and losses. This is one of the few computer simulations that can
actually get a room of people cheering! * MAZE MOUSE — The mouse with a mind! The computer
generates random mazes of whatever size you specify, then searches for a way out! The second time, he'll
always go fastest route! A true display of artificial intelligence! Full graphics, mazes &
mouses! * AMOEBA KILLER — You command a one man submarine that has been shrunken to the size
of bacteria in this exciting graphic adventure! Injected into the president's bloodstream, your mission is to
destroy the deadly amoeba infection ravaging his body! * LOGIC — This popular game is based on
Mastermind but utilizes tactics that make it more exciting and challenging — has 2 levels of play to make
it fun for everyone. * SUBMARINER Shoot torpedoes at the enemy ships to get points. Fast action
graphics, arcade type game is exciting and fun for everybody!

*****

* * * * PACKAGE SIX **************

20 HOME FINANCIAL PROGRAMS — Figures amortization, annuities, depreciation rates, interest
tables, earned interest on savings and much, much more. These programs will get used again and again. A
must for the conscientious, inflation minded person.

*****

* PACKAGE SEVEN *************

BACKGAMMON S.O — 2 different skill levels make this game a challenge to average or advanced players.
(Not recommended for beginners). Looks for best possible move to beat you! FANTASTIC GRAPHICS.
Plays doubles and uses international rules. * SPEEO READING Increases your reading speed. Also
checks for comprehension of material. Great for teenagers and adults to improve reading skills. * PT 109
— Drop depth charges on moving subs. Lower depths get higher points in this fast action graphics
game. * YAHTZEE Play Yahtzee with the computer. This popular game is even more fun and
challenging against a TRS-80! * WALL STREET Can you turn your $50,000 into a million dollars?
That's the object of this great game. Simulates an actual stock market!

NOT AVAILABLE AT RETAIL STORES ANYWHERE

INSTRUCTION BOOK WITH EACH PKG.

ONLY 12.95 EACH!!!!

ALL PROGRAMS GUARANTEED TO LOAD
CASSETTE PACKAGES REQUIRE 16K LEVEL II
PACKAGES ON DISKETTE (32K) $5.00 EXTRA

«9

✓ S121

Send check. Money Order or Bank Card #

TO: SIMUTEK, P.O. BOX 35298
TUCSON, ARIZONA 85740
(602) 882-3948

PHONE ORDERS WELCOME!

I PLEASE ADD $2.50 POSTAGE & HANDLING PER ORDER
3 OR MORE PACKAGES GET 10% DISCOUNT

Converting a Bargain TV
to a Video Monitor

The Lancaster method really works!

Stephen E. Bach
Rte. 2, Box 50 A -1
Scottsville VA 24590

I t is common knowledge in the
microcomputer world that
television sets can be used for
video monitors, and many of us
are doing just that. I want to
share my experience in convert-
ing a relatively inexpensive,
12-inch black and white televi-
sion set to direct video entry.

I bought a Westport Model
RP-205BN television on sale at
Woolco for $69. It is all solid
state (except for the picture
tube, of course), operates from
12 V dc as well as 110 V ac and
has a power transformer that
isolates the whole unit electri-
cally from the ac line, consider-
ably reducing chance of shock.
There is also an earphone jack
that can be used as the entry
point for the video signal from
your video board/generator.

Last, and very important, is
that with the operating instruc-
tions comes a separate sheet
containing the complete sche-
matic diagram of theTV! This is
an unusual addition for a con-
sumer electronic item. It is a
deal hard to beat for the price,
especially in comparison with
the $149 monitors I see adver-
tised in the catalogs.

The Conversion Details

My guide for making the con-
version was Don Lancaster’s
The Cheap Video Cookbook . It
just so happens that the video
amplifier circuitry shown by
Lancaster on page 149 of his
book corresponds exactly to

the video amplifier circuitry in
the RP-205BN, including com-
ponent numbers (e.g., Q201, the
video amplifier and R113). It is
as if Lancaster was looking at
the schematic of the RP-205BN
when he wrote the book! For
those of us who are not used to
poking our way into TVs, it is re-
assuring to find such corre-
sponding information to use as
a guide.

The most important modifi-
cation-lifting Q201’s base
lead from the printed circuit
board— could hardly be easier.
All the leads of the transistor
are labeled on the top side of
the PC board (the transistor it-
self is easily found because

soldering and simply cut
Q201’s base lead above the
board; however, that would
leave a short lead to which you
could connect the miniature
coaxial cable.)

Don Lancaster describes the
general procedure well enough.
I will concentrate on the specif-
ics for this set. Connecting the
coax (I used RG-174U) to the
video detector output is espe-
cially easy on this set because
there is a test point prong,
TP12, so labeled both in Lan-
caster’s book and on the TV’s
schematic and located right
next to Q201 !

This test point in the original
set is connected directly to the

FROM VIDEO c ■

GENERATOR BOARD

• ImF

CERAMIC

— )l

IN9I4 (2)

-w 14

♦ 5V
:|i5on

TO TV SET

Fig. 1. Video output level modification.

most of the components on the
board are clearly labeled). You
don’t have to do lots of detec-
tive work on pin-outs and let
yourself be vulnerable to what I
call Murphy’s mix-ups.

I used some Solder-Wick to
remove the solder from the
printed circuit pad to which the
base lead of Q201 was joined. I
then gently pulled the lead out
of its hole in the board with a
pair of long-nose pliers, bend-
ing the lead slightly at the same
time and pushing the transistor
away from the hole also to ease
the task. The most difficult part
was over! (If you are nimble-
fingered and have small hands,
you can dispense with the de-

base lead of Q201. It couldn’t
have been more conveniently
situated either in the circuit or
on the PC board. It becomes for
us the terminal of the TV’s vid-
eo detector output on the PC
board. It was simple, then, to
solder the center conductor of
the coax going to the video de-
tector output to this test point
prong and the shield of the
cable is to the nearby tin shield
of the TV’s I.F. section.

The other cable going to the
ex-earphone jack is connected
to Q201. The center conductor
is soldered to the base lead of
Q201, and the coax shield can
be soldered to the same tin
shield as was that of the other

piece of coax.

Actually, instead of using the
earphone jack for the video in-
put, I installed an extra jack
next to it toward the back of the
set; it waseasiertodothatthan
to remove the wires and solder
from the earphone jack. They
are small themselves, and the
space is a bit cramped. This
completed the chief modifica-
tion.

Lancaster recommends re-
moving the 4.5 MHz sound trap
of the TV to improve the video
bandwidth and transient re-
sponse. On this Westport TV,
the 4.5 MHz trap is a series res-
onant circuit made up of C201
and L201. To disable the trap I
cut with an X-acto knife the PC
board foil connecting C201 and
L201. Across that cut I con-
nected a miniature SPST switch
by which I can reinsert the
sound trap if ever I want to use
the set again as a TV. I mounted
the switch on the bottom of the
TV between a couple of the ven-
tilation slots in the plastic
case.

After all- that, I have been
able to observe only a slight dif-
ference in display quality be-
tween the two switch positions.
You could probably do without
the modification.

I am using the Xitex SCT-100
video board for my display. Its
video output level is 1.5 V peak-
to-peak. This is not quite
enough to drive the TV’s video
amplifier, so I had to change
this level to match that required
by the video amplifier. This
modification is simple with
Lancaster’s book as a guide
(see p. 159 of The Cheap Video
Cookbook. For a slightly longer
treatment of the problem, see

160 Microcomputing January 1980

Lancaster’s TV Typewriter
Cookbook, pp. 189-190).

I used two 1N914 silicon di-
odes in series as shown in Fig.
1. Two were enough. I mounted
the diodes, capacitor and resis-
tor close to the Xitex board in
its enclosure. Finally, per Lan-
caster’s recommendation (p.
150), I removed the lightning
protection resistor (in this set it
was 1 megohm) mounted near
the antenna terminals.

Final Adjustments

On completing these modifi-
cations I hooked up the Xitex
board to the TV via the new jack
I installed and filled the screen
with characters. The Xitex board
generates 16 lines of 64 charac-

ters each. This number of char-
acters pushes the screen’s ca-
pacity to its limits. I found that
the whole display was off cen-
ter to the right and that the
characters were not exactly
vertical but leaning to the left
slightly.

I went to the horizontal hold
adjustment, a variable inductor
next to the vertical hold on the
back of the set. (I had the back
of the TV off since the holes in
the case were not well aligned
with the adjustments’ slots.)
The horizontal hold adjustment
requires a square tuning tool to
fit the slug, which I did not
have.

With a small piece of printed
circuit fiberglass filed down to

size at one end, I adjusted the
horizontal hold until the char-
acters were all oriented straight
up and down with no slant.
This, however, shifted the
whole body of characters over
to the right so much that sev-
eral columns were completely
off the screen. I remedied this
by moving one of the ring mag-
nets on the CRT’s neck (Don
Lancaster shows them in Fig.
3-33., p. 152, and has a note
about them on page 153). I
moved the one whose tab is
toward the white flyback
transformer.

When I moved the tab initial-
ly, the other ring magnet moved
with it; they were lightly stuck
together. I held that one and

moved the first one. In this way,
I was able to shift the whole
body of characters back to the
center of the screen. The verti-
cal orientation of the charac-
ters was preserved. The display
looks OK.

These easy-to-make changes
and adjustments in a common-
ly available, inexpensive televi-
sion set have given me a good
quality video monitor for my mi-
crocomputer. I would encour-
age anyone beginning in micro-
computing or anyone upgrad-
ing his or her system by adding
a video display to do it in this
way. I’ll be happy to try to an-
swer any questions you might
have, but please include an
SASE.B

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Leedex Video 100 12” Monitor 119.00

Anderson-Jacobsen 841 Selectric (par) 1015.00

Heath WH-19 Terminal (fact asm.) 770.00

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p* Reader Service— see page 227

Microcomputing January 1980 161

MAILROOM PLUS

Make Your TRS 80 Work Like A Mini-IBM!

Mailroom Plus was developed for the National Rifle Association membership mailings. It features
sorting by last name or member number in addition to zip code. The program will sort 500 names
in 30-40 minutes, kill duplicates, and close up the file. Mailroom Plus will also search all records
for category, name, state, zip (or any other search code) and print these records on labels or in
tabular form. It separates large files into smaller ones by state or zip or merges small files into one
large one. Mailroom Plus is available on 32-48K disk for $75.00 by first class mail. Order yours to-
day postpaid.

THE PERIPHERAL PEOPLE ^P52
PO Box 524, Mercer Island, WA 98040

Master Charge and VISA cards welcomed

\^sP

VIDEO
TERMINAL

Now. a completely self-contained video terminal card for less than SI 50.00.
Requires only an ASCII Keyboard and TV set to become a complete interactive
terminal for connection to your computers serial 10 port Two units available,
common features are: single 5V supply, crystal controlled sync and baud rates
Ito 9600 baud), computer and keyboard operated cursor control, parity error
and control, power on initialization, forward spaces, line feed, rev. line feeds,
home, return cursor, and clear to end of line. Power requirements are 5V at
900ma, output std. IV p-p video and serial TTL level data

Features:

Display

Characters

Baud Rates
Controls

TH3216

32 characters
by 16 lines
2 pages

Upper case ASCI I

300-9600

Read to/from
memory

$149.95

TH6416

64 characters
by 16 lines
scrolling

Upper/lower case
optional

110-9600

Scroll up or
down

$189.95

Price (kit)

Above prices include all 1C sockets

OPTIONS:

Power supply (mounts on board) $14.95

Video/RF Modulator, VD-1 6.95

Lower case option (TH6416 only) 14.95

Assembled, tested units, add 60.00

SiEEfVlE^

"TH 6416 shown above”

Frequency Counter

$89.95 KIT

You've requested it. and now It s here! The CT-50 Fre-
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Tap off a color TV with our adapter and get ultra ac-
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SPECIFICATIONS

Sensitivity less than 25MV
Frequency range 5Hz to 60MHz. typically 65MHz
Gate time 1 second. 1 10 second with automatic decimal
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Display 8 digit red LEO 4 height
Accuracy 2 ppm. 001 ppm with TV time base'

Input BNC. 1 meg ohm direct. 50 ohm with prescale option

Power 1 10 VAC 5 watts or 12 VOC A.f Amp

Size Approx 6 ’ x 4 " x 2". high quality aluminum case

PRICES

CT-50, 60 MHz Counter Kit $89.95

CT-50WT, 60 MHz counter, wired and tested $159.95

CT-600, 600 MHz prescaler option for CT-50, add. . $29.95

VIDEO TO RF

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TRANSISTORS

MODULATOR

555

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309K .99

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NPN 2N3904 type
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Convert any TV set to a
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75

many computer manufactur-
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RS232/TTL

TTL/RS232

“1

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1C SOCKETS
low profile

5/S1.00

741 OP-AMP
MINI DIP 10/S2.00

Converter kit
Complete kit $7.95

16 pin low profile

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MINI-KITS

FM WIRELESS MIKE KIT

Transmit up to 300’ to any FM
radio. Sensitive mike input re-
quires dynamic, crystal or ceram-
ic mike. Runs on 3 to 9 volts.

FM 1 $2.95

TONE DECODER KIT

A complete lone decoder on a single PC
Board Features 400 to 5000 Hi adfuslable
frequency range, voltage regulation 567 1C
Uaetui lor louch-ton* decoding tone P<*rsJ
detection, FSK fleiwod. signaling and many
other uses Use 7 lor 12 button tcuchtorve de-
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Complete Kit. TD-1 $4 96

LED

BLINKY KIT

A great attention goi-
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f-ashea 2 jumbo LEO*
use lor name badges,
buttons or warning
type panel lights
Complete Kit. 81-1 .

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$2 96

SUPER-SNOOP AMPLIFIER

A super -ten si live amplifier which will pick
up a pin drop at 15 leet 1 Great lor monitoring
baby's room or as a general purpose test
amplifier Full 2 watt* ot output, runs on 6 to
tPvoits. uses any type ot mike Requ'res8-45
ohm speaker

Complete Kit. BN-9 94.96

MUSIC LIGHTS KIT

See mukc come alive! 3 different lights
flicker with music or voice One light for
lows, one for the mid-range and one lor the
highs Each channel individual^ adjustable,
and drives up lo 300 watts Great tor parties,
band music, nila clubs and more
Complete Kit. ML-1 97.96

SIREN KIT

Produces upward ana downward wa>i char-
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put. runt on 3-9 volte, usei 8-45 ohm

C4uneteta Kit. SM 3 92 96

POWER SUPPLY KIT

quilled power supply p
5 volls at 200ma and *5

Kit PS-3LT 96.96

A.C. POWER
CONTROL for ALL
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COMPLETE TURNKEY
SYSTEMS

Interface TO the Real World with GIMIX Relay
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Interface FROM the Real World with GIMIX

★ OPTO BOARDS (up to 34 switch closures with one 8 bit
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★ 16 BUTTON KEYPADS

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MAINFRAME: Includes chassis, power
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16K Static RAM
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• Gold bus connectors

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s 298 13

Memories . . .

As above
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s 368 18

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BKPROM BOARD $ 98.34

4K PPD PROM BOARD, Burner and Duplicator ... 198.35

2708’s each 7.90

64 or 32x16 VIDEO BOARD 198.71

80 x 24 SUPER VIDEO BOARD with user programmable RAM

character generator 458.76

Serial I/O’s 1 PortS 88.41 4 Port 198.43

Parallel I/Os. ...2 Port $ 88.42 8 Port 198.45

Add $5. handling charge on orders under $200.

cimix

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CHICAGO, ILLINOIS 60609
(312) 927-5510 • TWX 910-221-4055
Quality Electronic products since 1975.

TRS-80, Apple II
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It makes your
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MicroMint introduces a new wireless
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Busy Box $79.95

Cable and connector for TRS-80 14.95

Cable and adapter for Apple II 29.95

Cable and adapter for S-100 34.95

Power Supply (necessary for TRS-80) 9.95
Introductory Special:

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For TRS-80 including cable
and power supply 99.95

For Apple II

including cable and adapter 104.95

NY residents add 7% sales tax.

To order call (516) 374-6793
or write: The MicroMint Inc.

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Dealer inquiries invited.

TRS-80 is trademark of Tandy Corp.

Apple II is trademark of Apple Computer

MICROCOMPUTER SOFTWARE

(Floppy and hard disk systems)

• Medical Systems for Doctors

• Word Processing for Attorneys

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Software Review Staff

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Fortran

for the 8080 only $9995

• FORT//80 Is a subset of Fortran IV with many powerful enhancements!

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| • F0RT//80 directly addresses 8080 ports as • Fast; Runs up to 10 times as fast as PLM

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statements • Interrupt and interrupt control

I • FORT//80 accepts embedded in-line machine code • FORT//80 control of interrupts and interrupt
I • 8080 condition codes are available as FORTRAN service lines

keywords and can be operated upon • All code runs on 8080, 8085 and Z80 (upward

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----

I FORT//80 CPM version and manual on 8" diskette $99.95 1

FORT/ /80 Language manual separately 20.00

FORT/ /80 Implementation manual 20.00

Sample diskette validation program and data 5.00

Shipping charges to US and Canada postpaid, overseas add $5.00. Please add |
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1 1 . FORT / /80 is supplied on a single use basis, subject to the signing of a non-disclo- |
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| 2. FORT/ /80 can be implemented with other disc operating systems using the |
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BOX 4072, ROCHESTER, NY 14610
PHONE ORDERS CALL 716-271-6487

Distributors:

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• Electrolabs Inc., Box 6721, Stanford, CA 94305, (415) 321-5601

• Arkansas Systems Inc., 8901 Kanis Rd., Little Rock, KS 72205, (501) 227 84/1
♦Arkon Electronics Ltd., 409 Queen St. W., Toronto, ONT M5V 2A5, (416) 868-1315

Dealer inquiries invited.

™Akron Electronics Ltd.

is 0 Reader Service— see page 227

Microcomputing January 1980 163

Load Your SWTP at
4800+ Baud

The author tried JPC Products’ cassette interface and found it reliable to 9600 baud.

Jerry L Hunt
6709 Forsythia
Springfield VA 22150

W hile your Kansas City
Standard tape is loading,
do you:

A. Tap your fingers impatiently?

B. Yell at your kids and dog?

C. Rebuild your keyboard?

D. Take a correspondence
course in brain surgery?

If you would like to spend less
time fussin’ and fumin’ and
more time computin’, read on.

Since I’ve had a computer,
I’ve spent several man-days
waiting for my KC tapes to load.
This has become limiting, as
well as irritating. After becom-
ing fed up, I started looking for a

medium with a bit more speed.
My search first took me to the
obvious devices such as digital
tape decks and floppy disks.
These gadgets have two com-
mon characteristics: quickness
and expense. The first char-
acteristic is very attractive, but
the second is not as appealing.

One evening, while waiting for
a tape to load and browsing
through a Microcomputing mag-
azine, I noticed an ad from JPC
Products Co., PO Box 5615,
Albuquerque NM 87185, for a
$49.95, 4800 baud tape interface
bit that plugged into an SWTP
I/O port. I looked at the remain-
ing 10 minutes of KC tape still to
be loaded and ordered the inter-
face!

About three weeks (and

several more hours of KC tape
loading) later, the package was
delivered. It consisted of the
hardware and a comprehensive
hardware/software manual. The
kit went together with ease.
Hookup was equally easy and
consisted of soldering two
shielded cables to the con-
nector and plugging them into a
suitable cassette device.

Building Up Speed

Due to the high speed of the
data flow — up to 9600
baud— two factors are impor-
tant. High-quality tape is essen-
tial, as is a high-quality cassette
machine. The manufacturer rec-
ommends only top of the line,
low-noise tapes and provides a
recommendation list of cas-
sette recorders and decks. Ba-
sically, a good stereo tape deck
and tapes should be used.

My way of providing these
was to remove the stereo tape
deck and tapes from my com-
ponent stereo system. The deck
has two features that are useful
in this application: an accurate
tape counter and vu meters (out-
put meters). Also helpful were
the record level and output level
controls.

The software documentation
provided included two pro-
grams: one for high-speed read
and write and one for KC read.
This type of interface is versatile
as well as fast, since it functions
almost entirely through soft-
ware. Thus, it can be pro-
grammed for nearly any format,

current or future! The data
transfer rate is controlled by
software constants and the
computer’s clock. A short pro-
gram is included to determine
your SWTP computer’s clock
rate, and constants are fur-
nished so that the baud rate is
variable up to 9600!

The manufacturer recom-
mends the baud rate be set at
2400 for system setup, and once
any bugs are exterminated, the
rate is set to the advertised 4800
baud. After all the time I had sat
listening to the whirring of my
cassette recorder, this sounded
like the speed of light! However,
I also believed if 4800 was good,
9600 would be great!

I inserted the proper con-
stants for 9600 baud in the pro-
gram and, much to my amaze-
ment, it worked! JPC Products
only guaranteed 4800 baud, but
mine has been playing great at
9600.

About one out of 20 loads re-
quires reloading, due to a
slipped byte somewhere, but
when the system indicates a
good load, I never find an error.
This system is much more re-
liable than my KC system.

The one factor I found some-
what uninspiring was the neces-
sity to boot in the read software
via our crawling friend, a KC
tape. It takes only about 30
seconds to load; however, I was
spoiled.

My SWTP system incorpo-
rates an MPA2 board, which will
accommodate 8K of EPROM,

TC-3 Hi-Speed Cassette Interface.

164 Microcomputing January 1980

0000

017

ED. AS.

032

IFFF

0100

Counter

Program

Counter

Beginning Address

Program

Start

Name

End

Ending Address

Entry

Address

Example 1.

and since the high-speed soft-
ware is relocatable, I burned a
2716 with it. Loading 8K now
takes only typing JC002 and
waiting only 12 seconds! It
takes only about 16 seconds at
4800 baud, probably due to soft-
ware overhead time, which is
not affected by the changeable
constants.

File Search Program

I now had a system almost as
fast as a disk, except for the file
search capabilities. I work
around this with a written list-
ing, the footage counter and the
output meters. My listing for a
program is shown in Example 1.

I first set the memory loca-
tions MA002 through MA005,

with the beginning and ending
addresses I wish the program
loaded into. You can put the pro-
gram anywhere, unlike KC Stan-
dard tapes.

Next, I fast-forward or rewind
the tape to one count prior to the
start point (16 for this program). I
then type JC002, press play on
the deck and monitor the output
meters for data output. At com-
pletion of a good load, the
system returns directly to
monitor control. If there is an er-
ror in the byte count read versus
the byte count set in A002-5, a
register dump will print prior to
return to monitor. Total time
from system start-up to opera-
tion in 8K is about 40 seconds.
Writing to tape is done in the

same manner with the write pro-
gram.

I also have the KC loader in
ROM, but I seldom use it since I
have left the AC-30 and recorder
on-line to load commercially
purchased BASIC tapes. I’m
hoping the company will give us
some software to patch their
operating system into popular
BASICS. If that happens, would
anyone like a good deal on an
AC-30 and a very tired cassette
recorder?

I’m currently working up soft-
ware that will allow me to type in
addresses more conveniently,
use one-letter commands for
control and allow one-letter
load-run commands.

As I mentioned earlier, good
tapes are essential. I have been
using Radio-Shack-certified
data tapes with excellent suc-
cess. I have also used top-of-
the-line, high-quality tapes from
various manufacturers with
good success, but anything less
doesn’t work! I like the Radio
Shack tapes also for their 20
minute length. That’s about

300 K bytes including inter-pro-
gram spaces! An additional fea-
ture of the interface (frosting on
the cake) is a fully buffered 8 bit
parallel output port.

Conclusion

I am immensely pleased with
this system. I recommend it
without reservation as the best
buy in town for fast, economical
off-line storage. My system cost
me only $49.95 for the interface.
If you need a good tape deck,
add about $80 to that. So for
less than $150 you can have a
4800 baud system capable of
storing one megabyte (60-
minute tape).

I have no association with
JPC Products, except for admir-
ing their product. I haven’t even
communicated with them, since
the interface and software oper-
ate flawlessly.

I have also just discovered
that JPC is offering software for
a cassette operating system,
file handling and basic patches.
My prayer is answered for about
$27 on cassette!*

IWEB * ASSOCIATES!

EXCLUSIVE II IIS-81 USERS

TSH0RT™- THE GREATEST SOFTWARE BUY OF THE YEAR! HAVE YOU BOUGHT YOURS YET?

Q

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if Ji

■1ST LOAD

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IIFT S-

RIGHTS

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GOSUB

RETURN

DEFUSR

GOTO

SYSTEM

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STRS'.

CHRSf

VARPTR

lEN;

ne:

SHORTHAND for LEVEL II and DISK BASIC

* TSHORT™ lets you type LEVEL II and/or DISK BASIC more
quickly and accurately than ever before. Save up to 90%
programming time and achieve 1 00% accuracy.

*31 preprogrammed statement keys.

* KUSTOM rM key, up to 64 characters — changeable anytime.

* 42 key decals (see picture). 10 are different for DISK users.

* A single, shifted-key entry types entire statement on screen.

* Fast, efficient machine language.

* Uses 580 bytes of LOW memory, i.e.: No MEM SIZE req'd.

* Comes on cassette, one side LEVEL II, the other for DOS.

* Compatible with DOS 2.1, 2.2, 2.3, NEWDOS, KBFIX, etc.

* DOS version loads to and executes from disk via TAPE DISK.
•Features self-entering commands: CONT; GOTO10; KUSTOM

(Self-enter optional)

*TSHORT W/4 page instruction manual . . . $9.95

OTHER PRODUCTS AND SERVICES:

TBEEP™For LEVEL II and DISK USERS - A self-contained
beeper. Alerts you with a pager-like tone when YOUR program
commands it I Simply plug in-line with the "AUX" cable from
your CPU and program In BASIC, i.e.: OUT 255, 1: FOR I =
1 to 300: NEXT: OUT 255,0. (Req's9V Batt.) $19.95

TBUFF™— For LEVEL II CASSETTE USERS. Prevent and elim-
inate forever, cassette relay sticking. TBUFF is no larger than an
ice cube and plugs in-line with the "REMote" cable to your
cassette recorder. (Specify cassette recorder make and model)
$ 9.98

TPAK™— C-10 blank tape cassettes. AGFA 611 high quality
tape — the best money can buy! We use this tape exclusively
for TSHORT. Pack of 10 with box and blank labels. . . .$12.95

COMING SOON: (Write for further details.)

TBASE™— A powerful DATA BASE MANAGER program sec.
ondtonone! for under $50.00

TCHAIN™— LEVEL II chaining utility — Preserve your variables
and arrays for multiple program use, or while EDITing, RUNing
or CLOADing Priced under $ 10.00

TSEL™- We'll convert your IBM SELECTRIC to a high quality
printer — pp control — 512 character buffer — special TRS-80
cable with control switches — complete and ready to LPRINT
(cleaning, minor service included) Priced under $800.00

DEALER INQUIRIES INVITED
Send check or money order to:

WEB ASSOCIATES •

TELEPHONE ORDERS: (714)559-6249

P.O.BOX 60-KG • MONROVIA, CA 91016

SORRY,

^ W2 ° NO C.O.D.'S
• (Calif, residents add 6% tax)

^ Reader Service— see page 227

Microcomputing January 1980 165

VERBATIM- ATHANA- BASF'

Floppy Diskettes for

ANY COMPUTER SYSTEM

8

ft

20

HUNDRED LOTS

10 for $3.65 ea. • 50 for $3.40 ea.

We reserve the right to ship either of the name brands that we carry.

5V4 Mini-floppies only $2®°

HUNDRED LOTS

10 for $3.10 ea. • 50 for $2.85 ea.

SPECIFY SIZE, TYPE, & COMPUTER

5V4 " Soft Sector, 10 Sector, 16 Sector— 8" IBM Compatible, Soft Sector

CALL TOLL-FREE 24 HRS. TO ORDER

800-824-7888
OPERATOR 814

CALIFORNIA 800-852-7777

orC.O.D.

DC SOFTWARE & COMPUTER PRODUCTS

POST OFFICE BOX 503

SAN BRUNO, CALIF. 94066 ^

FOR INFORMATION 415-348-2387

Business Software for TRS-80

48k 2 drive system

Inventory Control—

1 000 Items /disk, full reports
Moiling List/ Phone Directory-
1000 listings/ disk, instant recoil,
machine language sort, prints labels
Business Moiling List—

1 500 listings /disk, multi-key search

02k 2 drive system
General Ledger-
200 accts., 1 750 transact., full reports
Accounts Payable—

200 accts., invoice linked, full reports

Accounts Receivable—

200 accts., invoice linked, full reports

Payroll—

Computes all deductions, prints
checks, statements, V-2, 941 -A

02k 1 drive system

Word Processor-
full feature editing, unlimited formatting
Appointment Calendar—

Great for the Executive, prints calendar

Also Available — Full Series of Real Estate Software

write for details

Check or Money Order C.O. D. Orders - 1 0 % down

User Manuals $20/ refund, w. purchase • Data Sheets $.50 with SASE
California Residents add 6% Sales Tax

P.O. Dox 1222

Imperial Deach, CA 92032 (714) 429-9123

$299

$179

$199

$159

$159

$159

$249

$179

$99

SOFTWARE
FOR THE TRS-80'

NOW!

A LIGHT PEN
FOR THE TRS-80
AND

SOFTWARE
THAT USES IT!

QS LIGHT PEN. We have taken the excellent PhotoPoint light pen and packaged it with our
own custom software. You get the light pen, which plugs into your tape recorder, and an
instruction booklet that includes the software you need to interface a light pen to your own
BASIC programs. O ur software routines are in BASIC and a simple GOSUB puts the light
pen in action. Two program examples are included. The "menu select" mode lets you set up
selection squares anywhere you wish on the screen. The "screen location" mode searches for
the pen position and returns the screen address to the calling program. One 9V battery
required, not included. Light Pen - $1 9.95

SKETCH-80™ by Bob Christiansen. Use the QS light pen to draw figures on the TRS-80
screen. Figures are drawn at three times normal size. Then save your sketch in memory and
start another one. Your sketch can be displayed at normal size or at the enlarged size at
which they were drawn. Combine two or more sketches on the same screen. Save your
sketches to tape or disk. You can even ask the computer to print out the POKE values re-
quired to produce your sketch. This system program figures out how much memory your
TRS-80 has and allocates storage accordingly. Requires level II, 16K. On cassette - $14.95

THE FOLLOWING PROGRAMS REQUIRE LEVEL H, 16K, AND CAN BE
PLA YED WITH OR WITHOUT A LIGHT PEN.

POKER PETE™ by Dave Gubser. Play five
card draw poker one-on-one against an ani-
mated PETE. Watch PETE shuffle and deal
the cards. He will challenge you with bluffs,
raises, calls and folds in this winner-take-all
showdown. And watch out — PETE's got a
gun! Three levels of skill. Written in BASIC.

0 n cassette - $1 1 .95

LOWBALL POKER by Danny Shea. How low can you go? It's you against Micro Molly and
the lowest hand wins. That's the rule in lowball poker. This version plays the popular
Gardena, California rules. Don't take her for granted — Molly plays an excellent game.
Written in BASIC. On cassette - $11.95

RUMMY MASTER by Dave Gubser. Play rummy against the computer. Exceptional
graphics display your hand, the discards, and the cards that have been melded. You see your
opponent shuffle and deal out the cards. Tested in an arcade, this program was a big hit.
Written in BASIC. On cassette - $11.95

MATCH CARDS by Danny Shea; BANKSHOT by Bob Christiansen. Two programs on one
cassette. MATCH CARDS is a concentration-type game where you match numbers, letters,
or graphic shapes. For 1 or 2 players. Automatic scoring rates your recall ability. Written in
BASIC. BANKSHOT is a billiard-like game for those who think they know all the angles.
Hit the ball into the pocket, but you must hit a wall first. Written in BASIC with machine
language subroutines. Just CLOAD and RUN. For 1 or 2 players. On cassette - $9.95

THE FOLLOWING PROGRAMS REQUIRE LEVEL II, 16K, AND DO NOT
USE A LIGHT PEN.

FASTGAMMON™ by Bob Christiansen. Our popular machine language backgammon game
that started us in business. The computer plays against you and makes good moves instanta-
neously. Option to replay dice rolls from the previous game. An eight-page instruction
booklet is included. On cassette - $19.95

On diskette - $24.95

DEBUG by Bob Pierce. Debug machine language programs by stepping through one Z-80 in-
struction at a time. Relocatable. Several display options. Multiple break points. Modify
memory and registers. On cassette - $14.95

Z-80 DISASSEMBLER by Vic Tolomei. Decode machine language programs, including
TRS-80 ROM with this Z-80 Disassembler written in BASIC. Instruction mode prints out
machine code and Zilog mnemonics in standard format. Or use the ASCII mode which con-
verts machine language code to ASCII. On cassette - $14.95

QS

QUALITY SOFTWARE

6660 Reseda Blvd.. Suite 103. Reseda. CA. 91335
Telephone 24 hours, seven days a week (213) 344-6599

*^Q12

HOWTO ORDER: MasterCharge and Visa cardholders may telephone their orders and we
will deduct $1 from orders over $19 to compensate for phone charges. Or mail your order
to the address above. California residents add 6% sales tax. Orders outside North America
add $5 for registered airmail, pay in U.S. currency.

*"TRS-80" is a registered trademark of Tandy Corp.

166 Microcomputing January 1980

use TRcopy

WITH YOUR LEVEL II TRS-80*

TRcopy is a cassette tape copying system that lets
you SEE what your computer is reading.

COPY ANY CASSETTE TAPE * 0

With the TRcopy system you can copy any TRS-
80 Level n cassette tape whether it is coded in
Basic or in machine language. You can also copy
data created by programs and you can copy assem-
bler listings.

YOU CAN SEE THE DATA

As the tape is being loaded, you can SEE the
actual data bjrte-for-byte from the beginning to the
end of the program. Up to 320 bytes are displayed
at one time. ASCII characters are displayed on the
first line and hexadecimal code is displayed on the
following two lines. Data is displayed exactly as it
is input including memory locations and check sums.

IDENTIFY PROGRAMS

With TRcopy you can identify programs on cas-
sette tapes without written documentation because
you can SEE the filename. If you forget to label a
tape, you can use TRcopy to display the tape contents
and Identify the cassette.

VERIFY CASSETTE TAPES

With TRcopy you can verify both the original tape
and the tape copies. You can make certain that your
machine reads the original tape correctly and that it
makes byte-for-byte copies. TRcopy also counts as
it reads giving you the exact length of the data.

MAKE BACKUPS FOR YOUR PROGRAMS

Now you can make backup copies of your valuable
programs. Many times a cassette that you make will
load better than one that is mass produced. The
original can then be kept as a backup in case the
copy is damaged.

MAKE COPIES OF YOUR SOFTWARE

If you are in the software business you can use
TRcopy to make tested copies of your programs for
sales distribution. TRcopy produces machine lan-
guage tapes that are more efficient than those pro-
duced by the assembler itself.

RECOVER FAULTY DATA

With TRcopy you can experiment with the volume
and level controls and you can SEE what the computer
is reading — even if your computer will not read the
data through normal read instructions! In this way it
is possible to read and copy faulty tapes by adjusting
the volume control until you SEE that the data is
input properly.

SIMPLE - FASCINATING - FUN

TRcopy is not only a practical utility program. It
is also a fascinating graphics program that lets you
SEE, for the first time, cassette data as your com-
puter is reading it. And it's as simple as 1-2-3.
Just load, verify and copy. You will now be able to
use cassette tapes with confidence knowing that
TRcopy is there when you need it.

The TRcopy system is a machine language program
with documentation explaining tape leaders, sync
bytes, check sums and other formatting conventions.
With the TRcopy system, you can SEE what you are
doing!

TRcopy System Including
Cassette Tape ond Documentation

QQ95

[SJjfiU&l

Orders accompanied by money order ^ rmiu

or cashier's check mailed same day.

Orders paid by other check shipped in 14 days. No COD's. Return
within 10 days for a full refund if you are not satisfied.

N.D. Orders Add ‘TRS-80 is o trademark “You cannot copy the
3% Soles Tax. of the Tandy Corporation. TRcopy cossette.

Data/Print

DEPT. KB. BOX 903. FARGO. N.D. 58107

DC

i E -

-

s i\

£ I ;
o z :

CJ i '

LU 2

OO s.

_ £ r « o

iS D50

TOLL FREE

SAME DAY
SHIPMENT

Don Lancaster's "Cheap Video”concept allows almost
unlimited options, including:

theULTIMATE in
CHEAP VIDEO

BOOK & KIT
ONLY $42.95

* Scrolling- Full performance cursor.

* Line/Character formats of 16/32, 24/80, 32/64 —
or almost anything.

* Graphics -up to 256 X 256 B&W; 96 X 128 COLOR

(requires low-cost option modules)

* Works with 6502 , 6800 and other micros.

SPECIAL OFFER: Buy the Kit (upper case alpha*
numeric option included) &get the Book at 1/2 price.
*^ p9 UiA ELECTRONICS, DEPT. K , 1020 W. WILSHIRE BLVD. OKLAHOMA CITY. OK 73116

! I’m Sold, PLEASE RUSH CD SEND FREE CATALOG

C D TVT-6Ev 8 Kit & Cheap Video Cookbook $42.95
C ) TVT -6 5 /8 Kit only (book required for assembly) -$39.95

name:.

* address*

I

j city: state: zip:

| HBi& ELECTRONICS. DEPT 1 K. 1020 WILSHIRE BLVD.. OKLAHOMA CITY. OK 73116

3 r

The Photopoint !f‘8 ht Pen

“a whole new concept in computer applications”

• All you have to do is Point to Play!

• 6 programs included — 3 on tape.

• Complete Info sheet on how to write your own
programs.

• Plugs directly into your TRS-80 system (Level II)

• Works with DOS too!

• Voids no Radio Shack warranties!!

• Over 500 sold . . .

Imagine, direct interaction with the video display.
Now you can eliminate the often confusing
keyboard from your real time
programs.

Order Your Photopoint Today

Micro Matrix
P.O. Box 938 ‘'""os

Pacifica, CA 94044

The only light pen approved by:

Quality Software/Instant Soft/Softside Mfg.

tS Reader Service— see page 227

Microcomputing January 1980 167

The compatible 8" TRS-80™ Floppy Disk

r THE SHUFFLEBOARD™

The Shuffleboard allows you to run
STANDARD CP/M. It's the perfect compliment
for your MAXI-DISK. Plugs right into your Z-80
socket and releases the lower 1 6K of memory
for use as RAM.

Now and only now can you run STANDARD
CP/M in the TRS-80.

An on-board bootstrap phantom ROM allows
you to instantly boot-up CP/M from your MAXI-
DISK at will.

Shuffleboard and CP/M (on 8" diskette) with
complete documentation $249

MAXI-DISK SPECIFICATIONS:

Drive type: Siemens FD 1 00-8
Capacity: 290 Kilobytes
Transfer rate: 250 kilobits/sec.

Latency (avg): 83 ms
I Access track to track: 6 ms
Head load time: 25 ms
Rotational speed: 360 rpm/Tracks: 77
Encoding method: FM
Size: 914" high x 18" deep x 4 wide
Cabinent color: gray

Send your check or money order to Parasitic
Engineering, Box 6314, Albany, CA 94706. Or
call BACMSA and MC orders to (415) 527-
6133, 10 A.M. to 4:30 P.M. PST.

The number one name in creative hardware design

PARASITIC ENGINEERING

TRS-80 is a trademark of Radio Shack and the Tandy Corp.
CP/M is a trademark of Digital Research. SHUFFLEBOARD &
MAXI-DISK are trademarks of PARASITIC ENGINEERING.

We re * 1 ! We've produced more TRS-80 8" floppy disk systems than any other manufacturer.

MAXI-DISK™ — FIRST FULL-SIZED

FLOPPY DISK FOR THE TRS-80

Runs TRS-DOS on 8" drives
Runs Standard CP/M™ *

Over three times the storage of Mini-Disk

Compatible with TRS-80 Mini-Disk, mix and match on same cable

Over a Megabyte on-line with four drives

Easy plug-in installation, soldering, trace cutting, or extra wires

Uses your expansion interface

Styled to co-ordinate with your existing system

Only $995.

* With Shuffleboard option

ADDITIONAL

$845

$995

SINGLE DRIVE,
INTERFACE AND
TRS-DOS PATCH . . .

P63

DR. DALEY presents
Software for the PET and the APPLE

Dr. Daley’s software is proud to announce
the release of a package of our best selling
programs.

These programs, regularly retailing for over
$400, have been assembled into a single

package for only $49.95. Included is our best
selling TREK3, CHECKBOOK, and a mailing
list, tutorials, games and puzzles for every
member of the family. All attractively
packaged in an album.

50 PROGRAMS ONLY $49.95*

♦After January 1, 1980 the price will be $69.95. Disk version $10 extra.

Your order will be shipped within four business days from receipt.

Charge your order to
MC/VISA

DR. DALEY, 425 Grove Avenue, Berrien Springs, Michigan 49103

i^D 43 Phone (616) 471-5514 Sun. thru Thurs., noon to 9 p.m. eastern time.

168 Microcomputing January 1980

TRANSITION ENTERPRISES, INC

We ore pleased to announce our entry into the
solor energy field. This industry is widely
recognized os being in a stage of development
similar to the microcomputing industry o few
years ogo. As we develop new products in this
area, we will moke them available through our
soles representatives. The EX50 (extender
board) and CI50 (control interface) will continue
to be ovoiloble from our dealers, and oil corre-
spondence should be addressed to them.

In England:

Sirius Cybernetics, Ltd.
7 Euston Place
Leamington Spa
Warwickshire, England

In the US:

In Switzerland:

Digicomp AG
Werdstrasse 36 v

8004 Zurich, Switzerland

\

Disney’s Electronics

6153 Fairmount Avenue

Suite 111 ^ T46

San Diego, CA 92120 f

Floppy Disks, printers & components

J name: |

i address: i

J city: state: zip: J

L BiyX ELECTRONICS. Dept.1- K 1020 W.Wilshi re, Oklahoma City. OK 7311 6 J

S P9

BASEX

MEANS SPEED!
BASEX is a fast, easy to learn
language for 8080, Z80, or
8085 microcomputers. Its
commands resemble BASIC,
making translation easy. An
interactive compiler permits
you to enter, list, edit and run programs up to lOx faster than
similar BASIC programs and use half the memory (2K plus pro-
gram).

Powerful features include:

Array variables
16 Bit Arithmetic/Logic
Variable name length
Named subroutines with
multiple arguments

* Text strings

* Versatile 1/0 Functions

* Block memory searches/
transfers

* Custom commands easily
added

CHOOSE YOUR BASEX...

* 97-Page BASEX manual (pub. by Byte Books) $ 8

* North Star Disk/Meca Alpha Tape/Paper Tape $25

* TRS-80 Level II, 16K tape with graphics commands $25

* CPM 8" Disk, with disk handler commands $35

* Basex Tape & Disk Guide-provides complete handlers

for North Star Disk and/or Meca Tape

(includes manual with source) $35

* Add $ .75 shipping (special 4th class) or $1.50 special

handling on all orders.

See BASEX at your local dealer or order direct from

Bfi B Interactive Microware, Inc. DEALER

™ o | ; ; ;■ 5* -g™., P . 16801 inquiries

(814) 238-8294 INVITED

E

i

s

e

L

a

e

t

o.

PET • PeT e PET e PET • PET • PET • PET • PET • PET • PET • PET • PET • PET • PET

PET PRODUCTS ^

Programs — Workbooks
for Floppy Disk — for Cassette

PROQRAM8 WORKBOOKS

! SW-1* MAILS mailing list system WB-1 Getting Started with Your PET

8W-2* CHECKBOOK record WB ' 2 prr 8,f1, HI •»* Array Handling

; SW-3* ACCOUNT8 keep track of who owes you how much ^ ° raph !?\

SW-4 MEDIT create and maintain data files Ca *** ttt 1/8

,w *‘ we<

I ‘These programs are special purpose data base management systems They all can:
e Sort numeric or string fields

• Select based on numeric or string (*)

• Select based on substring match

• Select based on range of entry number

j Prices: $9.90 each for programs using cassette storage for data

$12.95 each using sequential floppy disk storage for data.
Price inductee 40 - 60 page Instruction manual
i Add $2.00 for shipping and handling tis

P.O. Box 921. Dept KB

Money back guarantee

Loa Alamos. NM 87544

On bank card orders, give all numbers

e PET • PET e

*^T41 “

PET Is a trademark of Commodore Business Machines •

e PET • PET • PET • PET • PET e PET • PET • PET # PET e PET e PET

v* Reader Service— see page 227

Microcomputing January 1980 169

CLAfflFIEDS

Classified advertisements are intended for use by persons desiring to buy, sell or
trade used computer equipment. No commercial ads are accepted.

Two sizes of ads are available. The $5 box allows up to 5 lines of about 35 charac-
ters per line, including spaces and punctuation. The $10 box allows up to 10 lines.
Minimize use of capital letters to save space. No special layouts allowed. Payment is
required in advance with ad copy. We cannot bill or accept credit.

Advertising text and payment must reach us 60 days in advance of publication
(i.e., copy for March issue, mailed in February, must be here by Jan. 1). The publisher
reserves the right to refuse questionable or inapplicable advertisements. Mail copy
with payment to: Classifieds, Kilobaud Microcomputing, Peterborough NH 03458.
Do not include any other material with your ad as it may be delayed.

$$$$-WANTED—TRS-80s— WANTED—
$$$$ Any quantity, any condition, immedi-
ate cash available. Used TRS-80s and periph-
erals available. Write for firm cash offer.
Also used DEC PDP8, 1 1 CPUs, peripher-
als. Jim Simpson, Box 632, W. Caldwell NJ
07006. Tel. eves. (201) 226-9185.

Dual N. Star mini-floppies with controller,
cables and $700 accounts-receivable and
gen’l ledger software— $1000. Terminet
300B KSR RS-232 30 cps, $700. Integrand
mainframe, fully socketed, $275. Cromemco
A/R, A/P, G/L, Payroll & Inventory, $350
ea. J. Kelly, 400 W. Madison St., LaGrange
KY 40031. (502) 222-0465 evenings.

C1P, Superboard II Owners. Complete,
accurate, professional circuit diagram of 600
board; 17” x 22” print; $5. Circuit diagram
for TTY interface; $2. Pete Hitt, Box 266,
La Luz NM 88337.

TRS-80 computers used in evening adult
class. Several memory sizes, disks, Cen-
tronics 779 printers, latest modifications.
Some software. Jerry Scott, 717 Villa,
Watonga OK (405) 623-5805.

For Sale: RCA VIP micro with 4K RAM,
sound board, rf modulator, p.s., games and
utility programs on tapes. Cost $377; asking
$225. Call (617) 481-8543 in PM.

OSI C-1P w/20K RAM & 610 bd. Includes
floppy intfe. & KC std. tape intfe. 3 I/O
ports. Like new. $695. L. Gabrielson, 1038
4th St., Rensselaer NY 12144.

For Sale: Diablo Hytype I. Superb condi-
tion, includes full documentation, power
supply, stand, tractor and driving electronics
—$1500. Also Xybek “Prammer” 1702 pro-
grammer. Has 256 bytes of RAM and sock-
ets for 7 1702s (4 incl. with programmer). In-
struction manual and software on EPROM
is included— $75. R. C. Akeson, 12714 West
Hampton Ave., Butler WI 53007. (414) 781-
8820, days.

Going out of business— must sell. OSI Chal
III, dual flop, 32K OS65U Act IVB Micro-
term CRT, all in excel condition, no reas of-
fer refused. Software— utility, games, word
proc. Taylor Dist Co., 7530 E. Kenyon Ave.,
Denver CO 80237. (303) 779-1632. Sell sepa-
rately or together.

For Sale: Interact Model 1 computer, joy-
sticks, 15 games, Level I & II BASIC,
manuals, extra documentation; $400 (new).
Edgar Cormier, 1427-3 Rustic, Ocean NJ
07712.

Apple/ ALF music users interested in trading
songs contact Gary M. LaPoten, 333 North
Palm Drive, Beverly Hills CA 90210.

For Sale: ASR-33 TTY with paper tape read-
er/punch, modem, stand. $500, you pick up.
All back issues of Byte; $2.50 each. National
Multiplex tape cartridge system 3M3A for
S- 100, $175. Lenny Heath, 6618-D Lake Hill
Dr., Raleigh NC 27609. (919) 876-4168.

TEI Business Computer — 48K— with dual
drive 8” floppy, CPM operating system.
Professional machine. Costs $8995, will sell
for $4995. Call (816) 531-1050 for details.

For Sale: Heathkit ETW-3400 microproces-
sor trainer plus EE3401 program instruction
plus parts. $330 value for only $250 or best
offer. Great for beginners or children. John
Hansen, 314A Millett St., Wahiawa HI
96786. (808) 624-9690 or (808) 655-9721.

Heath H8, 8K RAM, ser I/O, keyboard,
video interface up and running, $600.
Charles Rapp, Jr., Rte 1, Box 51 A, Minooka
IL 60447. (815)467-5786.

Must Sell Immediately! Ex cond. IBM
Selecterm MDC mod 9710, 3 mo. No reas of-
fer refused. (303) 779-1632. Taylor Dist Co.,
7530 E. Kenyon Ave., Denver CO 80237.

For Sale: Imsai MIO board with mods to
make it work, 2 parallel ports, serial port,
Tarbell cassette port, software drivers, serial
port untested. 2 Imsai 4K RAM boards, 1
Godbout 8K Econoram board, 62 key ASCII
keyboard in dress enclosure. Make offer on
any or all. Roy Turner, 14407 Broadgreen,
Houston TX 77079. (713) 497-5849.

Free! TV Typewriter w/keyboard when you
buy my SWTP 6800 computer system w/12K
memory, AC-30 cassette interface, 4K + 8K
BASIC for only $550. Chris, (305) 259-4328.

Elf II, Giant, 4K, pwr, rf mod, BASIC, Pitt-
man, RCA, Osborne. Best offer. L. G., 334
Riverside, Palm Beach Gardens FL 33410.
(305) 622-6655.

Peripheral Dynamics 1555HT card reader.
Unused— reads 150 cards/minute. With
manual, only $400. (603) 485-9131. Mike
Vitale, 135 Main St., Suncook NH 03275.

Printer, 1 10 cps, 132 columns, 5x7 matrix,
up to 6 copies, adj. tractors, self test; like
new, just rebuilt by factory. This is a super
printer. With RS-232 interface, only $850.
PT factory assy. S-100 bus 8K RAM, $85.
IBM 3740 compatible floppy-disk controller
for use with Shugart, Siemens, Pertec or like
drives; controls one to four drives. With
manual containing S-100 and 6800 interface
instructions. Cost $850, only $250. H. H.
Hayden, POB 1275, Socorro NM 87801.

For Sale: PET 8K Model 2001; built-in
cassette, calculator keyboard. Mint condi-
tion! 6 mos. old, hardly used! With dust
cover, some programs. Asking $575.
Howard Braff, 34 Elk St., Hempstead NY
11550. (516) 489-6746 after 5.

For Sale: Back issue set of Kilobaud, in-
cludes #1-#15, #20-#27, #30-#34, must sell
as set; original Mark 8 minicomputer with
4K RAM, in quality cabinet, with Scelbi
software, schematics, will send photo; Iasis
microprocessor course. Best offer on any
item. John Boyd, 661 1 Burkett St., Houston
TX 77021. (713) 747-3977.

For Sale: OSI C1P 8K. Includes extended
monitor, editor /assembler and chess tapes.
Moving to C4P. $399 or best offer. Good
condition. Barry Beal, RFD #1 Box 160,
Machias ME 04654.

CORRECTIONS

The property gain/loss program associated with “Boy, Did I
Make a Killing!’’ (November 1979, p. 112) has three small omis-
sions. There are obvious blank spaces in lines 1340, 1450 and
1460. My smart printer should have put a “less than’’ sign in 1340
and an up arrow (raise to the power of) in 1450 and 1460.— Frank
J. Derfler, Jr.

The - 12 volt rail in Fig. 1 of “An Inexpensive and Easy EPROM
Board” (December 1979, p. 62) should be a -5 volt rail.

In my article, “The Apple Goes to Market” (November 1979, pp.
70-76), there is an error in line 5110, Listing 5. In order to properly
update the array, line 5110 should read:

5110 FOR I =Y TO X STEP -1: A(I) = A(I -1): NEXT: X = X-1: A(X) = B

In the article, X and Y were transposed, causing improper decre-
menting of the array. Sorry for any inconvenience this may have
caused. Thanks to George Culberson, W7CBU, who called from
Utah to point this out.— Leslie R. Schmeltz.

Fig. 2 of “Probos V” (October 1979, p. 78) should show pin 3 of
IC2 connected to pin 3 of IC1 , and pin 6 of IC2 connected to pin 4
of IC1 . It doesn’t matter if the logic probe is built directly from the
published schematic, but the corrected version will match up
more closely to the printed circuit pattern. In addition, the anode
of LED 3 (pulse indicator) should be shown connected to pin 8 of
IC1. Fig. 3 also contains an error; see the corrected figure here.

The address of Statewide Mortgage Corp. (November 1979, p.
8) should be PO Box 660, El Cerrito CA 94530.

The following changes should be made to the “Inventory” pro-
gram in the September 1979 issue. Also, the Sort subroutine
changes should be made to the version that uses the machine-
language sort routine.

170 Microcomputing January 1980

Here's what the Data Domain of Schaumburg IL says about the Dealer Directory:
"Yes! We want to continue with the Dealer Directory ad. The response this past year
has been good. We have had many people calling and visiting the store because they
have seen that ad. It is very cost effective, too!"

Hollywood CA

Largest selection of computer books in the
country. Software for the TRS-80, Apple, PET,
etc. Magazines. Open Monday-Saturday,
9:30-5:30. Opamp Technical Books, 1033 No.
Sycamore Ave., Los Angeles CA 90038,
464-4322.

Los Angeles CA

Featuring: PolyMorphic, North Star, Imsai,
Cromemco, Extensys, Speechlab products
and Poly-88 Users Group software exchange.
All products 10-20% off list. We won't be
undersold! A-A-A-A Discount Computer
How's, 1477 Barrington, Suite 17, Los Angeles
CA 90025, 477-8478.

Mountain View CA

Systems for business, industry and hobbyist.
Five terminals, ten printers and five main-
frames on display. Superbrain, Horizon
Quad, Compucolor II, Equibox and Altos
Computer System with hard disk. Much soft-
ware incl. CP/M, TRS-80 and PET Digital Deli
Computer Store, 80 W. El Camino Real, Mt.
View CA 94040, 961-2670.

San Francisco CA

Apple Specialists in business, personal and
custom applications. Full line of peripherals,
supplies and for leisure; sophisticated elec-
tronic games and video games. A.I.D.S., Inc.,
Artifical Intelligence Design Specialists, Inc.,
301 Balboa St., San Francisco CA, 221-8500.

Pompano Beach FL

Business systems, personal systems, whatever
the application, we can help. Consulting, pro-
gramming, education and maintenance. Ser-
vice, support and professionalism at afford-
able prices Computer Age Inc., 1308 N. Fed-
eral Hwy., Pompano Beach FL 33062, 946-
4999.

Venice FL

Discount prices & professional service: Cro-
memco, Northstar, Vector Graphic, DEC, Tl,
Thinker Toys, Intertube, Soroc, Centronics,
NEC, Selectric interfaces, Microdasys. Com-
plete business & medical billing software
available. MicroAge & Serendipity software
discounted. Sara-Tech Electronics, Inc., Com-
puter Division, PO Box 692, Venice FL 33595,
485-3559.

Aurora IL

Microcomputer systems for home or
business; peripherals, software, books &
magazines. Apple, North Star, Cromemco
systems. Also Tl 910 and the IDS-440 printer
w/Apple graphics. Farnsworth Computer
Center, 1891 N. Farnsworth Ave., Aurora IL
60505, 851-3888.

Chicago IL

Computer Hardware/Software Specialists for
home and business. Largest selection of com-
puter books, magazines and copyrighted soft-
ware in Chicago Metro area. Experienced fac-
tory trained service department. Feature
Apple and Alpha Microsystems and ac-
cessories. Data Domain of Schaumburg, 1612
E. Algonquin Road., Schaumburg IL 60195,
397-8700.

Naperville IL

Computer systems design, programming and
consultation by computer experts. Dealer for
SSM, Integrand, Tarbell, Ithaca Intersystems,
Verbatim, Diablo and others. Discount prices
on many items. Wilcox Enterprises, 25W178-
39th St., Naperville IL 60540, 420-8601.

Laurel MD

Exidy Sorcerer & accessories, Vista floppy-
disk systems, memory boards, software &
books, full line of ham & SWL equipment. The

Comm Center, Laurel Plaza, Rte. 198, Laurel
MD 20810, 792-0600.

Worcester MA

Computer products for personal and business
systems. Largest selection of software for
TRS-80, Apple, PET. Authorized Apple sales
and service Computer Packages Unlimited,
Centerwood Terrace, Route 12, West
Boylston MA 01583, 835-3428.

Garden City Ml

Complete systems for business, professional
and personal applications. Custom program-
ming available. Apple II, North Star, Vector
Graphic and other lines of microcomputers,
software, books, components. Computer
Center, 28251 Ford Rd., Garden City Ml
48135, 422-2570.

Grand Rapids Ml

Full-line microcomputer store. Ohio Scien-
tific— Equinox— PolyMorphic Systems —
Digital Systems — Codbout— Dynabyte —
Thinker Toys — Meca — North Star. Micro
Computer World, 313 Michigan St., N.E.,
Grand Rapids Ml 49503, 451-8972.

St. Louis MO

Experimenters' Paradise. Electronic and
mechanical components. Computer People,
Audio People, Hams, Robot Builders, Experi-
menters. Open six days a week. Gateway Elec-
tronics Corp., 8123-25 Page Blvd., St. Louis
MO 63130, 427-6116.

Lynbrook NY

Complete line of business computer hard-
ware, software & service. Design of special
software to suit your business. Specialists in
systems for truck routing & restaurants. Long
Island Computer General Store, Inc., 103
Atlantic Ave., Lynbrook NY 11563, 887-1500.

New York NY

Ohio Scientific distributor. Full stock, service
and software. Software for PET, Apple,
TRS-80 and hobbyist accessories (Jim Pack).

Aristo-Craft Computers, 314 Fifth Ave., Cor-
ner 32nd Str., New York NY 10001, 349-9034.

Akron OH

We've got it all. Business systems. Personal
systems. Software packages. Custom pro-
gramming. Terminals. Printers. Service and
books. Easy freeway access. 10 AM to 6 PM
Monday-Saturday. The Basic Computer
Shop, Fairlawn Plaza, 2671 West Market St.,
Akron OH 44313, 867-0808.

Canton OH

Cromemco. Ohio Scientific. Centronics
printers. Hazeltine terminals (CRT). Two-
dimensional plotter software for Cromemco,
as well as three-dimensional plotter software
for Cromemco. Business software. Mon.-Sat.
10-7. The Micro-Shop, 5686 Dressier Rd.,
North Canton OH 44720, 497-0847.

Kingston PA

We support Level II and Model II. Books,
magazines, programs, parts, accessories,
peripherals, free literature, free seminars,
cassettes, floppies, filters, transformers, caps,
chips, CRTs. Artco Electronics, 302 Wyoming
Ave., Kingston PA 18704, 287-1014.

Philadelphia/So. Jersey

Intertube II, immediate delivery. Free video
terminal comparison, Intertec's SuperBrain,
all Centronics printers, Omnitec data
modems/couplers, NCR portable modem ter-
minals, MFE digital cassette drives. L & S
Distributors, 44 So. Locust, Marlton NJ 08053,
983-7444.

York PA

SS-50 Buss Stop. Business & personal systems:
Smoke, SWTP, Gimix, MSI, Exidy, TSC, Com-
puterware, Jim-Pak, ACP, etc. Sales & service.
Closed Sunday G. Y. C. Co., 51 Hamilton
Avenue, York PA 17404, 854-0481.

Houston TX

Experimenters' Paradise! Electronic and me-
chanical components for computer people,
audio people, hams, robot builders, experi-
menters. Open six days a week Gateway Elec-
tronics, Inc., 8932 Clarkcrest, Houston TX
77063, 978-6575.

Dealers: Listings are $15 per month in prepaid quarterly payments, or one yearly payment of $150, also prepaid. Ads include 25 words describing
your products and services plus your company name, address and phone. (No area codes or merchandise prices, please.) Call Marcia at
603-924-7138 or write Kilobaud MICROCOMPUTING, Ad Department, Peterborough NH 03458.

replace lines 720 thpu 770 with the FOLLOWING! | Main program changes.

7 20 READ #0 X< T- 1 ) *64+5# A3 S

7 30 WRITE #0 XCR-1)*64+5#A3S#N0ENDHARK F ROW I 1 260 READ #0 I(P< I >-l )*64*5# RSM #0# P< I >#TAF( 5)#Pf NNFXTVCL0SE #0

7 40 READ #0 SCT-2>*64«5#A3S

7 50 WRITE #0 XCT-2>*64«5#A3S T 0* 1 260 READ #0 XCPC I >-l >*64+S# A3S\ ! »G* PC I)« TAB( 5 ># A3SVNEXTNCL0SE #0

Changes to “ Inventory ”

Sort subroutine changes.

A DD THE FOLLOWING TWO LINES

F RON! 4 30 P3-F3+1MF3VIF P<»0 THEN 530 ELSE IF AS«>~N** THEN 120 ELSE 600
T0f 4 30 P3«P3^1MP3MF P<»0 THEN 525 ELSE IF A$«>**N** THEN 120 ELSE 600

F RON! 140 FOR I«B TO N+B-1\K*CA1-I 1 >M 1*1 !♦!

525 OPEN #0#-pOINT-\FOR 1-1 TO YNWRITE #0»P( I# 1 )VNEXT

5 26 CLOSE #0 I T 0; 1 40 FOR I-B TO N+B- 1 \K* (A1~I1)\I1*I1 + 1MF I >ETHENEXIT 180

Microcomputing January 1980 171

D. E. Price

1265 Pine wood Dr.

Melbourne FL 32935

Hex and ASCII

Do it with an ASCII keyboard.

S everal months ago I set
out to improve my ac-
quaintance (then very lim-
ited) with microprocessors
and to learn the mechanics of
CPU interface. Experience
being the best teacher, I
elected to build from
"scratch," designing and
building as needed, rather
than assembling any of the
multitude of CPU kits cur-
rently available. This article is
a natural evolution of that
process and was put together
in hopes that other fledglings
might benefit from my
experience.

An interface module
capable of accepting the
ASCI I -coded outputs of a
low-priced keyboard was
needed (1) to convert certain
of those codes into hexa-
decimal codes; (2) to refor-
mat these codes to strobe out
two characters in parallel; (3)
to provide keyboard control
of a CPU.

There is a great tendency
in all of us (and I am equally
guilty as the rest) to approach
such a design problem from a
"new and exotic" viewpoint.
However, after the first pangs
of exoticism had passed and I
had returned to this earth, I

was able to work out a solu-
tion using commonly avail-
able components without
waiting for the postman to
deliver that one critical item
six weeks hence . . . post-
marked Timbuktu. This little
jewel will meet all the re-
quirements criteria at a price
that will astound you.

Overview

To begin with, examine
the keyboard output codes in
Table 1. Note that the four
lower-order bits for keys 0

Keyboard Code Formats
(Lower Four Bits Only)

KEY

HEX

ASCII

0

0000

0000

1

0001

0001

2

0010

0010

3

0011

0011

4

0100

0100

5

0101

0101

6

0110

0110

7

0111

0111

8

1000

1000

9

1001

1001

A

1010

0001

B

1011

0010

C

1100

0011

D

1101

0100

E

1110

0101

F

1111

0110

Table 1. Keyboard

output codes.

and 1 through 9 are identical
for both ASCII and hex but
that ASCII recycles bits 1
through 4 starting at alpha
character "A." Since we wish
to use alpha characters A
through F in hexadecimal, we
must convert that to provide
the essential hexadecimal
codes in Table 1. Now
examine the required versus
available codes for alpha char-
acters A through F in Table 1
again and note that adding
the binary weight of 1001 to
each character should provide
the needed conversion to hex.

We have now established
design criteria for the primary
function of this interface —
"pass numeric lower-order
bits unaltered but modify
alpha character lower-order
bits by adding nine." Estab-
lishing this criteria brings out
one more requirement — the
ability to discriminate be-
tween alpha and numeric
characters. Examine the
codes in Table 2 and you will
see that this discrimination
can be accomplished by bits
2 4 through 26 . All numerics
have a 01 1 code for these bits
while the alpha characters of
interest carry a 100 coding in
those same bits. Now, let's go

to Fig. 1 to apply what we
have found.

The Circuit

In Fig. 1, the two hex
inverters IC1 and IC2 provide
active low outputs for ASCII
codes 20 through 2 6 , an E
code and the keyboard
strobe. These inverters can be
eliminated if your particular
keyboard can provide both
true and false outputs for
each of the required codes.
Remember, saving two chips
here requires that the number
of conductors in the con-
necting cable be increased
and that some buffering be
lost at the conversion module
end of the cable — a false
economy!

IC3 examines bits 2^
through 2^. By using the false
levels for 2 4 and 2§, we
establish coincidence for a
low output at pin 12 for
hexadecimal codes A through
F. This output is inverted and
fed as a mode control line to
IC4 and IC6. A high on this
line means CONVERT; a low
prohibits conversion.

The necessary conversion
is accomplished (as we deter-
mined earlier) by adding 9 to
the alpha characters. We
could utilize a four-bit adder
or a PROM. However, a very
low-priced chip (e.g., 7486
exclusive OR) can accomplish
the same conversion if aided
by a couple of AND gates and
inverters.

The first step in the con-
version is to invert 2^ during
alpha characters. This is
readily accomplished by
feeding the mode control line
to pin 2 of the 7486. Look at
Fig. 1. You will see that any
level at XOR pin 12 will be
inverted only when pin 13 is
high. Thus, we add 8 only
during characters other than
numeric. Adding 1 to the
lower-order bit is more com-
plicated because "carries"
must be considered.

It is not the purpose of
this article to review the
basics of binary addition, so
please bear with me when I
say you must invert 2 1 if 2^
goes to a low as a result of
addition. Assuming that we

172 Microcomputing January 1980

do have a high mode line, pin
3 carries 2^ inverted. This
signal is, in turn, inverted by
a segment of IC2 and fed to
an AND gate segment of IC6
where it is passed only during
alpha characters (Mode Con-
trol input to pin 9). The
output of this gate, pin 8, is
fed to the 2^ segment of the
XOR, IC4, where it, in turn,
causes inversion of that

binary bit. This method of
addition and carry is rippled
up through bits 2^, 2^ and 22
to accomplish an add 1 for
these bits.

This ripple ''add and
carry" method works great
until you get to alpha char-
acter D. At this point our
"cheapy" method blows up
and senses a false inversion on
bit 2^ of the output causing

bit 22 to be inverted, with
the result of D showing an
output code of 1001 or the
equivalent of a numeric 9.

The first two segments of
IC1 and NOR gate IC5 are
utilized to inhibit AND gate
IC6-A on character D, thus
preserving our ripple and
carry approach. False inputs
of 2^ and 2^ are fed to IC5,
causing it to go low on the

output only during character
D (examine Table 1 once
again, only the D of alpha
characters A-F has lows in 2^
and 2\ simultaneously). This
low on IC5 is what inhibits
the conversion during char-
acter D. Pins 3, 6, 8 and 1 1 of
the XOR carry the hex code
outputs.

Our next step is to refor-
mat these hex codes to strobe

E

0

0

0

0

0

0

0

0

1

2 6

0

0

0

0

1

1

i

1

0

2 5

0

0

1

1

0

0

i

1

0

23

22

2 1

2 o

24

0

1

0

1

0

1

0

1

0

N

B

0

0

0

0

U

s

0

@

P

R

L

p

K

§

C

0

0

0

1

0

!

1

A

Q

T

H

L

S

C

0

0

1

0

T

2

B

R

L

X

R

E

H

0

0

1

1

T

#

3

C

S

1

X

S

E

0

1

0

0

0

$

4

D

T

L

T

B

E

0

1

0

1

N

%

5

E

U

R

Q

B

A

0

1

1

0

C

&

6

F

V

K

B

0

1

1

1

E

1

7

G

w

L

1

0

0

0

B

(

8

H

X

S

T

1

0

0

1

A

)

9

1

Y

B

1

0

1

0

L

*

J

z

F

1

0

1

1

V

+

K

[

T

1

1

0

0

F

<

L

\

F

1

1

0

1

C

_

_

M

]

R

E

1

1

1

0

S

•

>

N

A

s

0

c

D

1

1

1

1

S

/

?

0

E

1

L

Table 2. ASCII codes for Archer keyboard.

Microcomputing January 1980 173

v CHARACTER
REFORMATTER
FIG. 2

STR O 5 je^>0^ O STROBE

two characters out in parallel,
meeting the 8-bit bus require-
ment of many of the popular
CPUs. Fig. 2 is a single func-
tion diagram of the "shape-up
and ship-out" reformatter.
The requirement is to rec-
ognize when the operator
wants to output a hex-
formatted code. This recog-
nition is accomplished by
I Cl , an 8-bit NAND gate. By
feeding this gate appropriate
true and false (2^ and 2®)
ASCII outputs 2^ through
26 , a low is achieved from a
semicolon key.

IC4 is a 5-bit shift register.
The inverted output of the
recognition chip (pin 2, IC2)
is combined with the key-
board strobe in AND gate
IC3A to provide a load signal
for the shift register, loading
a 10000 sequence upon
receipt of a ; signal. The clock
for the shift register is pro-
vided at pin 6 of IC3B. This
clock is inhibited while the
keyboard is active with a
semicolon. A four-bit latch is
activated by the first parallel
output bit (7496-15) and,
therefore, loads the first hex
character appearing on lines
20 through 2^ of the code
converter as shown in Fig. 1.

When the keyboard strobe
appears after keying in the
first hex character, the shift
register shifts to the right to
output a parallel code 01000.
This code latches the first hex

Fig. 1. ASCI / /hex converter.

word in IC5 and holds same
as an interim memory. Out-
puts of the 4-bit latch are
routed through a four-
channel bilateral switch (IC6)
to the CPU data bus
through D?. The four lines 2^
through 2^ from the code
converter are also routed
through a four-channel bi-
lateral switch (IC7) to CPU
data bus bits through D^.

When the second hex
character is entered from the
keyboard, it is inhibited from
entering the 4-bit latch due to
the previous shifted pattern
of the shift register. The shift

register, moving once more to
the right with the keyboard
strobe, enables AND gate
IC3-C via pin 9, allowing the
keyboard strobe to pass
through this AND gate and
enabling the CPU to strobe
the two characters held at the
bilateral gates (IC6, 7) onto
the CPU data bus in parallel.
These bilateral gates also
appear as Tri-state outputs to
the data bus, effectively pre-
venting the loading of the bus
except during the strobe
pulse from the CPU when
either 1 or 0 is presented to
each of the 8 CPU data lines.

So far we have met two of
our initial three objectives:
We have provided code con-
version, ASCII to hex, and
reformatted to strobe out
two hex characters in parallel
to the CPU. It should be
noted that while this process
is being followed, the key-
board simultaneously pro-
vides ASCII-coded output
one character at a time for
character presentation on a
TVT. The diagram for CPU
control is presented in Fig. 3.

External Keyboard Control

In Fig. 3, IC3 and IC4 are
each a control pair com-
prising AND gates cross-
connected to latch in com-
mands from a decoder, IC2.

The Archer keyboard used
in this project presents an E
bit on 2? output. This E bit
appears for six non-ASCII-
coded keys: BREAK, CTRL,
CLEAR, HERE IS and two
unmarked, uncommitted
keys. The 7442 decoder (IC2)
in Fig. 3 functions as a rec-
ognition circuit for these keys
when presented with true
signals from 2^ through 2^
plus a strobed E s input.
NAND gate IC1 provides the
strobed E signal and also
serves as an inverter to pro-
vide the necessary active low
input to IC2. The six decoded

ICI, 283 : PIN I4*Vcc,PIN 7* GND

+ 5 V

Fig. 2. Single function diagram of the character reformatter.

174 Microcomputing January 1980

♦5V + 5V

outputs appear as active low
signals for BREAK, CTRL,
CLEAR, HERE IS, LEFT
BLANK and RIGHT BLANK.

When directed to the
appropriate inputs of IC3 and
IC4 as shown in Fig. 3, four
keys have the ability to force
latched outputs at output
pins 1 A, IB. BREAK will
cause a low at pin 1 A and a
high at pin IB. This is WAIT
logic for an RCA COSMAC
CPU with which this interface
module is now working.
CLEAR causes a low on pin 1
of IC4 and a high at pin 1 of
IC3. This is CLEAR logic for
the same CPU. RUN provides
highs at both output ter-
minals, while HERE IS pro-
vides a LOAD function of
two lows at the same ter-
minals.

Summary

This concludes the descrip-
tion of the interface module
and its functions. Again, it is
not exotic in form, but it
does provide in a reliable
manner three essential func-

tions of code conversion, re-
formatting and CPU control.
It can be constructed without
real concern for critical lay-
out of lead dress (the original
was wire-wrapped on a Radio
Shack prototype board) and
all components are low cost
and possibly available in your
junk box.

In any event, the total

chip complement costs under
$5 at any of the several
houses advertising in this
magazine. The design is not
without shortcomings. It does
not provide for back-stepping
in the case of erroneous
entry, nor can it obviate
illegal entry such as the
keying in of shifted char-
acters . . . but what can you

expect for less than $5? Plans
are currently underway to
add back-spacing capability
for program correction and
rapid program step through
for entry verification. The
latter is considerably more
useful to limited systems
without CRT display than to
those lucky people with TVT
connections. ■

We bought 350,000 LED’s.

And you get the savings.

Reds, greens, yellows, orange, small,
medium, large. Bags of 25 - mixed $2.75.
That’s only 11<t each. Compare this bargain up to
twice our price.

FACTORY PRIME

5BI - Polar LED 59C ea. or 10 for $5

LAB-BENCH VARIABLE POWER SUPPLY KIT

5 to 20 VDC at 1 AMP. Short circuit protected by current
limit. Uses 1C regulator and 10 AMP Power Darlington.
Very good regulation and low ripple. Kit includes PC
Board, all parts, large heatsink and shielded
transformer. 50 MV. TYP. Regulation. $15.99 KIT

CLOCK MODULE OPTIONS
MAI 008 A and D MA1013

Switches and pot for all options
Includes:

5 push buttons
1 toggle

1 10K pot $2.50

Alarm Parts (including high impedence
transducer) Much more efficient than a
speaker. $1.50

Transducer only (unbelievably loud!) $1.10

16K DYNAMIC RAM CHIP
WORKS IN TRS-80 OR APPLE II

16K X 1 Bits. 16 Pin Package Same as
Mostek 4116-4 250 NS access. 410 NS

LED 8AR GRAPH AND ANALOG METER DRIVER

New from National Semi. #LM3914. Drives 10 LED
directly for making bar graphs, audio power meters,
analog meters, LED oscilloscopes, etc. Units can be
stacked for more LED’s. A super versatile and truly
remarkable 1C. Just out!

SPECIAL PRICE: $3.99 INCLUDES 12 Page Spec. Sheet

cycle time. Our best price yet for this state
of the art RAM 32K and 64K RAM boards
using this chip are readily available These
are new fully guaranteed devices by a
major mfg.

VERY LIMITED STOCK!
“MAGAZINE SPECIAL’’ - 8/$79.50

NATIONAL SEMICONDUCTOR

‘COLOSSUS JR.” JUMBO CLOCK MODULE

MA1013
BRAND NEW!

Bright 4 digit 0.7" LED Display

Complete- Add only Transtormer and Switches

24 Hour Alarm Signal Output

12 Hour Real Time Format

50 or 60 Hz Operation

Power Failure Indication

LED Brightness Control

Sleep and Snooze Timers

Alarm "on” and PM Indicators

Direct Drive - No RFI

Direct Replacement for MA1012

Comes with Full Data

SONY 23 WATT AUDIO AMP MODULE

#STK-054. 23 WATTS SUPER CLEAN AUDIO. 20 HZ to
100 KHZ + 2 DB. HYBRID, SILICON, SELF-
CONTAINED MODULE. ONLY 1% x 2Vfe IN. WITH
DATA.

COMPARE AT UP TO TWICE OUR PRICE! $6.50 each

60 Hz CRYSTAL TIME BASE
$4.95 (Complete Kit)

Uses MM5369 CMOS divider 1C

MICRO MINI
TOGGLE SWITCHES
6 for $5 with hardware.

with high accuracy 3.579545
MHZ Crystal. Use with all MOS
Clock Chips or Modules. Draws
only 1 .5 MA. All parts, data and
PC Board included. 100 Hz.
same as above, except $5.95

Sound Activated Switch not a
kit. Already assembled. Clap
your hands and turn on lights,
music boxes, coffee pots, etc.
Full spec, sheet with each unit.

690 ea. 10 for $5.50

FAIRCHILD PNP
“SUPER TRANSISTOR”

2N4402. TO-92 Plastic. Silicon PNP
Driver. High Current. VCEO-40 HFE-
50 to 150 at 150 M A. FT-150MH2. A
super "BEEFED-UP" Version of the
2N3906. _ ___

8 FOR $1.19

JUMBO IC ASSORTMENT

All new not rejects. BIG
computer mfg. Surplus. Some
standard marked, many house
numbered. TTL, DTL, LINEAR.
All prime. 1st line.

50 for $1.59 500 for $12.95

TOSHIBA POWER AUDIO AMP

5.8 WATTS RMS Typical Output. 50 to 30,000 HZ
+ 3 DB. For CB’s, tape decks, PA’s, etc. Works off
of asingle supply voltage from 10.5to 18VDC. 10
Pin plastic DIP with special built in heat sink tab.
Perfect for use on 12VDC. $Q99
With Data. each

Digital Research: Parts

^ (OF TEXAS)

P.O. BOX 401247 • GARLAND, TEXAS 75040 • (214) 271-2461

TERMS: Add 50C postage, we pay balance. Orders under $15 add
75C handling. No C.O.D. We accept Visa, MasterCharge and
American Express cards. Tex. Res. add 5% Tax. Foreign orders
(except Canada) add 20% P&H. 90 Day Money Back Guarantee on
all items.

Write for our free catalog full of many useful bargains.

~ J

Microcomputing January 1980 175

SECURITY for TRS-80 DISC DRIVE OWNERS

• BUSINESSMEN - Ensure the privacy of your Corporate Files

• PROGRAMMERS - Protect Programs/Data Files

• RS232 USERS - Foil wiretaps with Super Cipher

• AMATEUR RADIO - Baffle eavesdroppers with Super Cipher

CIPHER for security at the Confidential level. Cipher is a sophisticated icryptographic system
which is impervious to all Master DOS passwords. Codes of up to 11 alphanumeric
$39.95 characters accepted. Cipher is supplied with its own self-chaining disk operating
system, but will accept DOS 2.1, 2.2 or 2.3 files.

SUPER CIPHER for security at the Top Secret level. Super Cipher accepts codes of up to
256 alphanumeric characters. This is the code for special business or military applica-
$99.95 tions.

AUTHORS - DISTRIBUTORS - SYSTEM HOUSES

• DOUBLE AND TRIPLE YOUR SALES

• CURTAIL COPYRIGHT VIOLATIONS

• PREVENT ILLEGAL DISC DUPLICATION

• THWART PROGRAM EXAMINATION DURING EXECUTION

We will customize your program so that it will execute, but can not be examined regardless of any effort to disable the protection.
Our technique is impervious to both Master DOS passwords and alien DOS systems. Send us your program together with a $40 encipher-
ment fee. If we consider the cryptographic problem acceptable, we will encipher your program and return the encrypted version to
you. Otherwise your $40 fee will be promptly refunded. Examine and test our diskette - complete with its own copyrighted DOS system
- to see if the level of encipherment is adequate. If you are satisfied we will then supply duplicates in lots of fifty at a fixed charge per
diskette.

P.O. Box 516 • Troy, Idaho 83871 • SOLARIS PRESS • Specify 32K or 48K • (208) 835-5391 ^S123

TRS MOD I and MOD II PROGRAMS FROM t-RACET computes^

oo BASIC for Level II and Disk Systems $49.95

Full MATRIX Functions - 30 BASIC commands! !

Mathematical and common matrix functions. Change arrays in
mid-program. Complete array handling. Tape array read and write,
including strings. Common subroutine calls. ,

Over 50 more STRING Functions as BASIC commands!! String
manipulation, translation, compression, copying, search, screen
control, pointer manipulation and utility functions. Includes
multikey multivariable machine language sorts. Load only machine
language functions that you want! Where you want in memory!
Relocating linking loader! More than you ever expected! !

oo BUSINESS (Requires Infinite BASIC) $29.95

20 Business oriented functions including:

Printer Automatic Pagination with headers and footers!

Packed Decimal Arithmetic ( + , -, *,/) 127 digits!

Binary array searched and hash code generator!

COMPROC Command Processor for Disk Systems $19.95

Auto your disk to perform any sequence of DOS commands,
machine language loads, BASIC, memory size, run program,
respond to input statements, etc. Single BASIC command file
defines execution! Includes auto key-debounce, screen print and
lower case software driver.

New Products Jan/Feb! We answer reader response inquiries! !

ATTN / System Houses - We license usage of our routines!

TRS Add-On OEM’s - Direct BASIC commands tailored
for your hardware.

REMODEL + PROLOAD Specify 16, 32, or 48K Memory $34.95

RENUMBER any portion or all of BASIC program. Line references
adjusted.

MOVE any portion of a BASIC program from one location to
another.

DELETE lines or ranges of lines while using the utility.

MERGE all or any portion of a program from tape. (Load lines
300-500 from your tape to existing program at line 1000 with
renumbering on the way in!)

SAVE combined/merged programs, or any portion to tape with
VERIFY.

COPSYS Copy Systems Tapes (Editor/Assembler Format) $14.95
GSF(16, 32, or 48K) $24.95

18 Machine language routines using ‘USR’ calls. Includes RACET
sorts, array handling, and fast lines and scrolls.

DOSORT (Specify 32 or 48K • 2 disk minimum) $34.95

Sort/Merge multi-diskette sequential files. Multiple keys and
variables. Includes GSF - machine language sorts, comparators
and string handling.

MOD II SUPPORT

RACET is supporting the MOD II!!

Call or write for current information! We have a MOD II Superzap
and other assembly language tools!

Ask your dealer if he carries our products!

DEALERS! We will work with you directly or through our
distributors.

— ^ R24 —

g- RACET COMPUTES -T=]
702 Palmdale, Orange CA 92665

CHECK, VISA, M/C, C.O.D. • Calif. Residents add 6% • Telephone Orders Accepted (714) 637-5016

WHEN ORDERING PLEASE ADVISE PUBLICATION SOURCE

DATA TERMINAL EQUIPMENT — FROM MICROMAIL

LA34 DECwriter IV

* 1 , 199. 00

• Upper/lower case, 9x7 dot matrix

• 10, 12, 13.2, 16.5 characters/inch

• 2, 3, 4, 6, 8 or 12 lines/inch

• 22”W x 7”H x 15Vfc”D, 25 lbs.

• 110 or 300 baud, RS 232C serial
ASCII

• Friction feed, paper width to 15”

New

from DIABLO

DIABL0 1640 *2,690.°°
Receive-only $2,331.°°

High-quality daisywheel printing at
45 cps.

DIABLO 1650 * 2,779.°°
Receive-only *2,419.°°

Metal daisywheel printing at 40 cps.

T.1. 810 printer *1,695.°°

• Includes upper/lower case

• 150 characters per second

• RS 232C serial interface

• Adjustable forms tractor

SOROC IQ 120 *795.°°

• RS 232C, upper/lower case, full
ASCII

• Numeric keypad, protected fields

• Cursor keys plus addressable cur-
sor

• Auxiliary extension port

S0R0C IQ 140 *1,250.°°

• RS 232C and 20mA current loop

• Extensive editing features

• 25th line terminal status display

• 16 function keys (32 with shift)

NEC Spinwriter

Call or write for prices

To Order: Send certified check (personal or company checks require
two weeks to clear) including handling* and 6% sales tax if delivered
within California.

* Handling: Less than $2,000, add 2%; over $2,000, add 1%. Everything
shipped freight collect in factory cartons with manufacturer’s warranty.

Want to

REALLY UNDERSTAND
The BASIC Language?

From the author of the highly acclaimed TRS-80 Users/
Learners Manual comes the book you’ve been asking for! The
BASIC Handbook is THE definitive reference and "idea” book,
explaining in detail the BASIC language as used in over 50
favorite micros, minis and mainframes.

It’s not a dictionary, and not a textbook, but a virtual ENCYCLOPEDIA of the
BASIC language. In it is everything you need to know about the most
important BASIC statements, functions, operators and commands, explained
in a way that you can put them right to work.

This HANDBOOK is written to be used!

With the BASIC Handbook you can finally make those programs found in
magazines run on your computer - or know the reason why they can’t.

If there is an alternate way to write a program using other BASIC words, the
Handbook shows you how. If there is a function needed but your machine
doesn t have it, the Handbook gives you a subroutine that accomplishes the
same thing. About the only thing it won’t help you with is an additional 16K of
memory.

Is TRS-80 Level II covered - YES!

Is PET covered - YES!

Is Apple covered - YES!

Sorcerer, AlCair, Imsai, Etc.

YES .... and over 50 more!

A°

COMPUSOFT - PUBLISHING

A Division of CompuSoft. Inc

8643 Navajo Road

San Diego. California 92119

360 pages
Soft Cover

30-Day money back
Guarantee

4 ?

A&

A*> ^

P n&

-o\o

^ &

i^C109

I understand my handbook will be shipped promptly and there
is a 30-day money back guarantee

My Computer is a

v* Reader Service— see page 227

Microcomputing January 1980 177

THE PERFECT
CHRISTMAS GIFT

ORDER NOW
FOR CHRISTMAS

CdmpuCduer'

GROW WITH US AS
COMPUCOVER EXPANDS
TO MEET YOUR NEEDS
IN THE 1980’s
Dealer Inquires Invited
Club Discounts Available

• Cloth Backed Naugalhyde Vinyl

• Waterproof & Dustproof

• Longer Life

• Improved Reliability

• Three Decorator Colors
Saddle Tan • Electra Blue • Black

TO ORDER:

Include $1.00 for
Postage & Handling
Send Check or Money Order To
CompuCover
P.O. Box 324 Dept. A
Mary Esther, FL 32569
Phone (904) 243-5793

TRS-80

Keyboard $7.95

Cassette 3.95

Video Display 9.95

Set 19.95

APPLE II

Keyboard $9.95

Disk 3.95

Set 11.95

Sorcerer $9.95

TRS-80 Disk 4.95

Double Disk 6.95

Percom Disk 4.95

LoboDisk 6.95

Matchless Disk. . . .6.95

CENTRONICS

779 $17.95

730 9.95

P-l 9.95

DECWRITER

36 $19.95

120 19.95

Wang Terminal .$18.95
Wang w/disk .. .22.95
Trendcom 100 . . . .9.95

Soroc IQ 120 18.95

Pet 19.95

★ EXCITING MAILORDER DISCOUNTS ★

NOVATION CAT

ACOUSTIC MODEM

• ANSWER. ORIGINATE

• 300 BAUD

• BELL 103

• LOW PROFILE DESIGN

* 179 °°

MICROPOLIS" MetaFloppy.

DRIVES

1043 (Single) 31 5Kb $995°°
1 053 (Dual) 630Kb $1695 °°

•QUAD DENSITY DESIGN
•COST EFFECTIVE STORAGE
•4 TIMES STANDARD CAPACITY
EVEN AFTER FORMATTING!

wippkz U l6k

^^l)R APPLE n PLUS

*975°°

COLOR . GRAPHICS . SOUND
APPLE DISK U $495.00

INCLUDES CONTROLLER

PORTABLE MINISCOPES

LOW POWER CONSUMPTION

MS-1 5 SINGLE TRACE 1 5 MHz $ 289
MS-21 5 DUAL TRACE 1 5 MHz $ 389
MS-230 DUAL TRACE 30 MHz $ 519

SOROC IQ 120

• SERIAL RS232C

- • FULL ASC II UPPER/LOWER CASE

• NUMERIC KEYPAD CURSER KEYS

• SCREEN CONTROL &

PROTECTED FIELDS

* 775 °°

LEEDEX VIDEO 100

12" BLACK & WHITE MONITOR

• VIDEO BANDWIDTH 12MHz±3db

• COMPOSITE VIDEO INPUT

* 129 °°

SD EXPANDORAM

•64K S-1 00 DYNAMIC RAM BOARD
•WORKS WITH Z-80. 8080 & 8085
•POWER CONSUMPTION 5 WATTS
•BANK SELECT -PHANTOM REFRESH
•NO WAIT STATES REQUIRED

WITHOUT MEMORY_

16KKIT

32K KIT

48K KIT

64 K KIT

ADD $50 FOR ASSEMBLED & TESTED

.$149 00
_215 00
_269 00

349 00

_ 409 00
✓'Cl 74

• TO ORDER .

Phone orders invited, using credit cards Or send personal
check or money order Add 1% for packing and handling
California resident add 6% sales tax All equipment is
shipped freight collect in factory carton with manufacturers
warranty All equipment subject to availability and price
change without notice

VISA

OMPUTER SPECIALTIES

6363 CL CAJON BIVO., SUITE 205,
SAN DliOO, CA. 02115 • (714) 570-0330

178 Microcomputing January 1980

Z-80/TRS-80™ Users

BOOK YOU’VE WANTED NOW CAN BE YOURS
THE Z-80: HOW IT WORKS

(THE PROGRAMMERS PERSPECTIVE)

By Monte Corum

Best Most Complete Reference Yet
cpu Operation Explained
Addressing Modes Demystified
Register Functions Described
Instructions Defined
Interrupts Diagrammed
Cycles Outlined Formats Described
Execution Described in Text,

Notation and Diagrams
Meaningful Analysis of 698 Commands
in Formatted, Usable Tables
Simple, Consistent Notation and Formats
A Programmer’s Book, Beginner or Experienced
Ideal Text for Class Instruction
Pricse: $17.95 Plus Tax and Shipping
VISA & MSTRCHRG-NUMBER AND EXP. DATE
PREPAID WE SHIP

MICROWARE ASSOCIATES, INCORPORATED
9301 N. 58th St. DPT. AAA
SCOTTSDALE, AZ. 85253

DEALER INQUIRIES INVITED

™ TRS-80 IS A TRADEMARK OF TANDY CORP.

A PROFESSIONAL DATA BASE
MANAGER FOR NORTH STAR
OPERATING SYSTEMS.

If you've been struggling with random access pointers, churning out
pages of BASIC code every time your program needs a newfile, then DBMS-1
is for you!

This data base management system allows you to dynamically create
files with up to ten named, variable length fields. Alpha, numeric and space-
saving table lookup fields are supported. Your data is stored linked sequential
and automatically arranged binary tree fashion for fast, keyed searches.
Records can be amended, deleted, listed alphabetically or summed on
multiple keys.

Sophisticated "Wild Card" search procedures allow nearly limitless
sorting possibilities. There are extensive "help" routines (for instance, you
can recall your field names, parameters and record numbers at any time).

But best of all, DBMS-1 performs ALL searching and sorting IN PLACE.
That means your files don't have to be in RAM. Access to files by other
programs is easy — DBMS-1 provides header and record sizes and other
information on request.

The DBMS-1 system is a series of linking modules which run under
NORTH STAR BASIC, Release 4.0 or 5.0 with a minimum of 12K of RAM.

Price of the Diskette is $125. (US), which includes a fully commented
version of DBMS-1 and a condensed "Go" file. A sample data file is included
for experimentation. The extensive user's manual may be ordered separately
for $15., refundable on purchase of the DBMS-1. One year’s FREE update
service is also yours.

Order Post Paid From:

THE SOFTWARE DIVISION

LAKE CITY TECHNICAL PRODUCTS

No. 5 - 1952 SPALL ROAD

KELOWNA. BRITISH COLUMBIA ,xL27

CANADA V1Y4R1

OWNERS

Right now is the perfect time to
give the gift of knowledge to your-
self and your family.

•100 Favorite House Plants*

CAN BE THAT GIFT!

Discover how to determine the amount
of light your house plants are getting
with little more than your own
hand. Discover a one finger technique!
for deciding when to water your
plants and how much. Discover a unique
way to show how practical your home com-
puter is for the home when you demonstrate
it for friends. Why wait? Know you are
giving your house plants everything they need.

cecunk

*100 FAVORITE HOUSEPLANTS*

FOR TRS- 80 4K LI $12.50

4K Lll $12.50

(Idaho Residents Add 3% Sales Tax)

MAKE CHECK OR MONEY ORDER PAYABLE TO:

CECDAT Inc. P.O.Box 8963 Moscow. Idaho 63643

lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll■llllll■IIIIIIIIIIIIMIIII

TRS-80 PERIPHERALS

DISKDRIVES
40 tracks,
with power supply & case
VERBATIM DISKETTES $3.00
DYSAN DISKETTES $4.60
4 DRIVE CABLE $45.00

16K MEMORY KIT

300 NS $70.00

250 NS $76.00

200 NS $85.00

w/complete instructions^
Jumpers add $2.50 /j

PRINTERS from
CENTRONICS, INTEGRAL
DATA, NEC SPINWRITER,
TEXAS INSTRUMENTS.
ALL AT GREAT SAVINGS!!

We also carry APPLE, SORCERER, PET, SO SALES products. WE WILL NOT BE UNDERSOLD.

GAMES

ANDROID NIM $14.00
Nim robots that wink and
respond. Excellent graph-
ics and sound.

STAR TREK III $14.00
Travel through the galaxy
,on the Enterprise and de-
stroy klingdns. New up-
dated version.

AIR RAID $14.00

Real time shooting gal-
lery.

SARGONrCHESS . $19.00
Best chess for TRS-80

LIBRARY 100 $49.00

100 games, utilities, and
business programs in one
package. Great value!
SPACE BATTLE

by Lv4 $14.95

Disk $19.95

ADVENTURE
by Scott Adams. ..$14.95
(ea) for Sorcerer or TRS-80
TRS-80 32K Version$24.95

TRS-80 SOFTWARE

UTILITIES

NEWDOS 4 $99.00

Enhanced DOS. Contains
many improvements over
TRSDOS. 7 useful utilities
built in. For 40 track use
also.

NEWDOS $49.00

Same as above without,
utilities.

SYSTEM INTEGRATION

TEST $29.00

tests memory, disk drives,
and printer.

MICROSOFT FORTRAN

325.00

CPM $150.00

RENUMBER $14.00

disk $17.00

G2 LEVEL III $49.00

FOUTH by MSS $35.00
GSF by Racet Computers
$24.95

TRS-80 computers in stock!!

BUSINESS

GL, AR, AP, PAYROLL
INTERACTIVE . $350.00
Reports include unbilled
invoices, open/closed ac-
counts, ageing. Trial bal-
ance, income statement,
balance sheet. Handles
200 accounts, 1750 trans-
actions. Stand alone on
each $95

INVENTORY II $99.00

activity listing, complete
listing, selected listing,
minimum quantity search,
1000 items per disk.

ALL ABOVE PROGRAMS
BY SBSG

ELECTRIC PENCIL. $99.00
by Michael Shrayer

disk $150.00

BEST word processor for
Ihe TRS-80

XMAS SPECIAL j

C.O.D

TflS-30© TANDY CORP.

I 1 0% Discount on
J all Software orders
I over $100

The above list is just a brief summary of some of our most popular software. We have a large selection of other
software for many uses and for many computers. Documentation for any of our programs is available on re-
quest. If you have any questions, please call. We would like to hear from you.

TO ORDER. CALL OR WRITE:

MIDWEST COMPUTER PERIPHERALS ." M106
P.O. BOX 437
WILMETTE IL. 60091

Prices Subject to Change without Notice

iiiiiiiiiiiiiiiiiiuiiiiiiiiiiiiiiiiiiiiiiiiiiaiiiiiiiiiiimiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiiiiiiiii

v* Reader Service— see page 227

Microcomputing January 1980 179

Interrupting BASIC

With this article and a source listing , you can do it.

d. h. wants
£ H. Wiser
NC State University
Box 5906
Raleigh NC 27650

W e have been devel-
oping an 8080-based
microprocessor system for data
acquisition and environmental
control in greenhouses used for
energy research. The data ac-
quisition function requires as
many as 15 data points to be
read periodically (some as often
as once per minute) and the data
processed for output at half-
hour intervals. The control func-
tion requires certain points to be
read and the information pro-
cessed on 15 second cycles so

that heaters, vent fans and cool-
ing pads can be properly con-
trolled. A further requirement is
that the system be capable of re-
sponding to commands entered
from the keyboard at any time.

Data acquisition and control
functions can easily be handled
with polling loops, but in this
application the requirement for
random access to the control
and data acquisition program
made polling cumbersome.
Utilizing interrupts to initiate ac-
tion seemed to provide the
answer, but it also presented us
with a problem. We want to pro-
gram mostly in BASIC, rather
than assembly language, but
the BASIC interpreters available
have no provisions for servicing
interrupts.

This article discusses three
approaches developed to over-

come this problem: (1) handling
the interrupt in assembly lan-
guage with a return to the point
of interrupt in the BASIC pro-
gram; (2) handling the interrupt
in BASIC with no return to the
point of interrupt; (3) handling
the interrupt in BASIC with a re-
turn to the point of interrupt in
the BASIC program. Each ap-
proach has advantages and dis-
advantages that depend on the
particular application.

The BASIC interpreter we
used is Cromemco’s 3K Control
BASIC (CB), but all the tech-
niques used should apply to
other Interpreters, provided you
have access to the source list-
ing for the interpreter. A fully
commented source listing is
easier to work with, but it can be
done with just a listing from a
disassembler if you’re
dedicated enough and are pro-
ficient at reading assembly lan-
guage.

Handling Interrupts in
Assembly Language

The simplest way to handle

interrupts is to process them in
an assembly-language subrou-
tine with a return to the BASIC
program that was executing at
the time of interrupt. Table
1 shows the assembly language
required, and Fig. 1 shows the
activity flow between the CB
programming and the interrupt
handler. Our system has vec-
tored interrupt capability so that
eight separate interrupt signals
can be handled, each causing
transfer to one of eight different
memory locations between
%0000 and %003F. (The % sym-
bol is used to designate hexa-
decimal numbers throughout
the text. The exception is in the
assembly listings, where hex
numbers are suffixed with an H
according to standard practice.)

An El (enable interrupt) com-
mand must be executed before
the microprocessor will recog-
nize an interrupt, and a mask
word is required to disable un-
wanted interrupts. These steps
are included in the initialization
routine ‘INIT’.

We chose the interrupt that

INTERRUPT

CONTROL BASIC
PROGRAMMING

RETURN

ASSEMBLY LANGUAGE
INTERRUPT HANDLER

INTERRUPT

TRANSFER-

PROGRAM TRANSFER ►

Fig. 2b. Activity flow for limited handling of interrupts in BASIC, Version II.

Fig. 2a. Activity flow for limited handling of interrupts in BASIC, Version I.
180 Microcomputing January 1980

transfers control to location
%0008 and masks the rest. The
JMP instruction at %0008 trans-
fers control to %0040 where the
interrupt service (which can be
any assembly-language routine)
is executed. Control is then
returned to the BASIC program
at the point of interrupt.

Note that the status word and
registers must be saved in order
to reenter the interrupted pro-
gram. Note also that the inter-
rupt service includes an El com-
mand because the micropro-
cessor disables interrupts as
soon as an interrupt is received.
Initiation of interrupt service is
done by typing a CALL %0060.

This approach is simple and
effective, provided that the task
to be performed during interrupt
service does not require math-
ematical computation or exten-
sive manipulation. It requires lit-
tle knowledge of the interpreter
itself, beyond knowing where
the interrupt handler can be
stored. CB does not use the first
two pages of memory, so loca-
tions up to %01 FF are available.

A way to use BASIC to man-
ipulate data read during the in-
terrupt is available when
variables are stored at fixed lo-
cations. CB stores 52 variables
denoted by letters A through Z
and AO through ZO in the first
104 bytes of memory page 3
( % 0200 - % 0267). The interrupt
handler can be used to store
data at these locations. A
BASIC program could be used
to test the contents to deter-

0008

C3 40 00

JMP INTR

0040

F5

INTR

PUSH PSW

/SAVE STATUS WORD AND REGISTER

0041

E5

PUSH H

/CONTENTS ON CB STACK.

0042

D5

PUSH D

0043

C5

PUSH B

/PROCESS INTERRUPT: ANY ASSEMBLY

/LANGUAGE PROGRAM CAN BE PLACED

Interrupt

Processing

/HERE. THE SPACE NEED NOT BE

goes here

/RESTRICTIVE IF SUBROUTINES AND

/JUMPS ARE USED.

00 5 A

Cl

POP B

/RESTORE REGISTER CONTENTS AND

005B

D1

POP D

/STATUS WORD.

005C

El

POP H

00 5D

FI

POP PSW

005E

FB

El

/ENABLE INTERRUPTS AND RETURN.

005F

C9

RET

0060

3E FD

INIT

MVI A.OFDH

/THIS SUBROUTINE INITIALIZES THE

0062

D3 OA

OUT 10

/INTERRUPTS: A MASK WORD IS OUTPUT

0064

FB

El

/TO ELIMINATE UNWANTED INTERRUPTS

0065

C9

RET

/(NOTE: THE ACTUAL MASK WORD AND

PSW

EQU 6

/OUTPUT PORT ARE SYSTEM DEPENDENT.

/CHECK YOUR SYSTEM MANUAL FOR
/DETAILS). ENABLE INTERRUPTS AND
/RETURN .

Table 1. Assembly-language programming and machine code for handling interrupts.

(Memory Page 4)

10

REM

INITIALIZATION

20

REM

LOAD MACHINE CODE

FOR INTERRUPT SERVICE ROUTINE, 'LOAD' (FIGURE 3)

30

PUT ( %0040 ) = %06 , %07,

%11, %69, %02, %21, %59, %00

40

PUT ( %0048 ) = %7E, %12,

%13, %23, %05, %C2 t %48, %00

50

PUT(%0050) = %1B, %1B,

%21 , %00, %00, %FB, %C3 , %42

60

PUT(%0058) = %E4, %52,

%55, %4E, %20, %36, %0D, %FF

70

REM

LOAD MACHINE CODE

FOR INITIALIZATION ROUTINE, 'INIT*

80

PUT(%0060) = %3E , %FD,

%D3, %0A, %FB, %C9

90

REM

SET JUMP AT %0008

100

PUT(%0008) = %C3, %40,

%00

110

REM

OTHER INITIALIZATION GOES HERE, IF ANY

120

REM

ENABLE INTERRUPTS

BY CALLING 'INIT'

130

CALL %0060

140

STOP

(Memory Page 6)

10

REM

INTERRUPT HANDLER

20

REM

ANY PROCESSING GOES HERE

30

REM

ENTER IDLE LOOP TO WAIT FOR NEXT INTERRUPT

40

GOTO

40

50

STOP

Table 2a. BASIC programming for limited interrupts, Version 1.

mine whether an interrupt had
occurred. This is the procedure
recommended by Mits for use
with the Altair real-time clock.

Limited Interrupt Handling
in BASIC

Handling interrupts in assem-
bly language is fairly difficult if
calculation or output is re-
quired. There are obvious advan-
tages of programming in BASIC
to handle these situations, but
this necessarily requires more
knowledge of the programming
of the interpreter. This approach
is a relatively limited one that
has some practical applica-
tions.

Suppose the main program
does essentially nothing until
an interrupt occurs. The inter-

(Memory Page 4)

10

REM

INITIALIZATION

20

REM

LOAD MACHINE CODE FOR INTERRUPT SERVICE ROUTINE ('LOAD') HERE

30

REM

LOAD MACHINE CODE FOR INITIALIZATION ROUTINE ('INIT') HERE

40

REM

SET JUMP AT %0008

50

REM

OTHER INITIALIZATION GOES HERE, IF ANY

60

REM

ENABLE INTERRUPTS BY CALLING 'INIT'

70

STOP

(Memory Page 6)

10

REM

INTERRUPT HANDLER

20

REM

ANY PROCESSING GOES HERE

30

REM

INTERPRETER RETURNS TO ITS OWN IDLE LOOP (NOT SHOWN) TO AWAIT INPUT

FROM KEYBOARD

(Memory Page 8)

10

REM

INTERRUPT HALT

20

REM

LOAD ASSEMBLY LANGUAGE TO PERFORM HALT

30

PUT(%0100) = %F3, %C9

40

REM

CALL HALT ROUTINE

F*)

CALL

%oioo

60

STOP

Table 2b. BASIC programming for limited interrupts, Version II.

Microcomputing January 1980 181

0008

C3

40

00

JMP

LOAD

0040

06

07

LOAD

MVI

B,7

/LOAD 'RUN 6' INTO INTERPRETER AND

0042

11

69

02

LX I

D.0269H

/JUMP TO BASIC: PUT LENGTH OF STRING

0045

21

59

00

LXI

H,STR

/(INCLUDING SPACES, CR , AND TRAILING

0048

7E

LP

MOV

A ,M

/FFH) INTO B, PUT COMMAND STRING

0049

12

STAX D

/LOCATION INTO DE , GET ASCII STRING

004 A

13

I NX

D

/'RUN 6' AND STORE IN COMMAND STRING

004B

23

I NX

H

/LOCATION, ENABLE INTERRUPTS AND JUMP

004 C

05

DCR

B

/TO THE INTERPRETER AT LOCATION E442H

004D

C2

48

00

JNZ

LP

0050

IB

DCX

D

0051

IB

DCX

D

0052

21

00

00

LXI

H ,0000

0055

FB

El

0056

C3

42

E4

JMP

0E442H

0059

52

55

4E

STR

ASC

'RUN 6'

/THIS IS THE ASCII STRING, 'RUN 6',

005C

20

36

/FOLLOWED BY A CR AND AN FFH.

005E

OD

FF

DW OFFODH

0060

3E

FD

INIT

MVI

A ,0FDH

/THIS SUBROUTINE INITIALIZES THE

0062

D3

OA

OUT

10

/INTERRUPTS: OUTPUT MASK WORD TO

0064

FB

El

/ELIMINATE UNWANTED INTERRUPTS.

0065

C9

RET

/ENABLE INTERRUPTS AND RETURN.

Table 3. Assembly-language programming and machine code for limited interrupt service .

(Memory Page 4)

10

REM

INITIALIZATION

20

REM

LOAD MACHINE CODE FOR INTERRUPT SERVICE ROUTINES HERE IF DESIRED

30

REM

LOAD MACHINE CODE FOR INITIALIZATION ROUTINE ('INIT') HERE

40

REM

SET JUMP AT %0008

50

REM

OTHER INITIALIZATION GOES HERE, IF ANY

60

REM

ENABLE INTERRUPTS BY CALLING 'INIT'

(Memory Page 6)

10

REM

INTERRUPT HANDLER

20

REM

ANY PROCESSING GOES HERE, RETURN WHEN FINISHED BY CALLING 'REPL '

30

CALL

%0096

Table 4. BASIC programming for full interrupt service.

rupt is serviced and then the pro-
gram waits for the next inter-
rupt. Provided that any interrupt
can be completely serviced
before the next one occurs, the
main program will always be in
an idle state at the time of inter-
rupt, and it is not necessary to
return to this point. This would
be true, for example, for inter-
rupts occurring on a regular
schedule, such as clock pulses,
but not true for random inter-
rupts coming from the keyboard
or from another device.

The BASIC program required
is shown in Table 2a and the
accompanying Fig. 2a. It con-
sists of three main parts: (1) an
initialization routine starting on
memory page 4; (2) the interrupt
handler starting on memory
page 6; (3) the idle loop following
the interrupt handler. The initial-
ization routine is executed first
by typing the command RUN.
This stores the machine code
for the assembly-language rou-
tines and performs any other ini-

tialization written in by the user.
The last step is to execute the
CALL %0060 command, which
will enable the interrupts.

Since there is usually an inter-
rupt request present when clock
signals are being used for inter-
rupting, execution of the El com-
mand will Initiate the interrupt
service, which in turn transfers
control to memory page 6. The
idle loop is entered when the in-
terrupt processing is finished.

A more sophisticated version
of the same program can be
written if we realize that the
interpreter provides a loop of its
own (while checking for key-
board input) that can take the
place of the idle loop. Return to
the Interpreter loop is accom-
plished by omitting the STOP
command from the routine
stored on memory page 6. When
Control BASIC encounters an
end-of-file before a STOP is
reached, the interpreter types
an OK and a > and enters the
loop waiting for input. This pro-

vides visual feedback to signify
the end of interrupt processing
and allows a short routine to be
executed from the keyboard if
desired (perhaps to disable in-
terrupts).

Table 2b shows this version of
the program with the idle loop at
the end of the interrupt handler

being eliminated and a routine,
added on memory page 8, which
loads a Dl (disable Interrupt)
command and a RET at %0100
and then executes a CALL
%0100 to stop the interrupts.
The routine is executed by typ-
ing RUN 8 while the keyboard is
active. This provides time to cor-
rect programming (during pro-
gram development), execute a
longer routine (say a memory
dump) or perform any function
desired by the user. The inter-
rupt service is restored by typing
a CALL %0060 command, which
reenables the interrupts and
starts the process again. The
interaction among the various
routines is shown in Figure 2b.

The execution of the routine
on memory page 6 is made pos-
sible by a feature of Control
BASIC that allows separate rou-
tines to be stored in different
pages of memory, and a RUN
command (followed by a page
number) transfers control to the
routine stored on that page. In
this case, the interrupt service
must create a RUN 6 and force
the interpreter to execute the
command as if it had been en-
tered from the keyboard. In
order to do that we had to deter-
mine how the interpreter han-
dled those commands.

When a command is entered
from the keyboard it is stored as
a character string in memory
locations starting at %0269. A
trailing carriage return (CR) and
%FF are added to denote the
end of the string, and the inter-
preter jumps to location %E442
with the contents of the DE reg-

INTEfiPUPT TRANSFERS

PROGRAM TRANSFERS ►

NOTE

POINT OF INTERRUPT CAN BE INTERRUPT HANOLER ALSO.

Fig. 3. Activity flow for full interrupts service in BASIC.

182 Microcomputing January 1980

0008

C3

6E

00

JMP SAVE

006E

F5-

SAVE

PUSH PSW

/SAVE STATUS WORD AND REGISTERS

006F

E5

PUSH H

/ON STACK.

0070

D5

PUSH D

0071

C5

PUSH B

0072

3E

OF

MVI A ,0FH

/SAVE CONTROL VARIABLES:

0074

21

DE

03

LXI H.03DEH

/LOAD NO. OF BYTE PAIRS INTO A; PUT

0077

CD

B7

00

CALL STORE

/DESTINATION INTO HL AND CALL STORE.

007A

3E

04

MVI A ,04H

/SAVE PORTION OF COMMAND STRING:

007C

21

69

02

LXI H,0269H

/LOAD NO. OF BYTE PAIRS REQUIRED BY

007F

CD

B7

00

CALL STORE

/RUN 6 (INCLUDING CR AND FFH) INTO A.

0082

2A

00

01

LHLD 0100H

/SAVE STACK POINTER ADDRESS: PUT

0085

EB

XCHG

/MEMORY POINTER IN DE ; PUT OLD STACK

0086

21

00

00

LXI H,0000H

/POINTER ADDRESS INTO HL , MOVE TO DE

0089

39

DAD SP

/AND RETURN MEMORY POINTER TO HL .

008 A

EB

XCHG

/STORE LOW BYTE OF OLD SP INTO

008B

73

MOV M,E

/MEMORY LOCATION ADDRESSED BY HL ,

008C

23

I NX H

/STORE HIGH BYTE IN HL + I ; INCREMENT

008D

72

MOV M,D

/HL TO POINT TO NEXT AVAILABLE

008E

23

I NX H

/MEMORY LOCATION AND STORE AT 0100H.

008F

22

00

01

SHLD 0100H

0092

FB

El

/ENABLE INTERRUPTS AND JUMP.

0093

C3

40

00

JMP LOAD

0096

2A

00

01

REPL

LHLD 0100H

/RETRIEVE STACK POINTER ADDRESS:

0099

2B

DCX H

/LOAD MEMORY POINTER FROM LOCATION

009 A

56

MOV D,M

/0100H; MOVE HIGH BYTE TO D; MOVE

009B

2B

DCX H

/LOW BYTE TO E; STORE NEW MEMORY

009C

5E

MOV E,M

/POINTER; MOVE OLD SP ADDRESS

009D

22

00

01

SHLD 0100H

/(IN DE) TO HL; MOVE CURRENT SP

00A0

EB

XCHG

/TO OLD POSITION TO RECLAIM STORED

00A1

F9

SPHL

/INFORMATION.

00A2

21

70

02

LXI H.0270H

/RESTORE OLD COMMAND: LOAD COMMAND

00A5

3E

04

MVI A ,04H

/STRING LOCATION INTO HL , NO. OF BYTE

00A7

CD

C3

00

CALL RETRV

/PAIRS INTO A, CALL RETRV.

00 AA

21

FB

03

LXI H.03FBH

/RESTORE OLD CONTROL VARIABLES: LOAD

00 AD

3E

OF

MVI A ,0FH

/ENDING LOCATION INTO HL; LOAD NO. OF

00 AF

CD

C3

00

CALL RETRV

/BYTE PAIRS INTO A, CALL RETRV.

00B2

Cl

POP B

/RESTORE REGISTERS AND STATUS WORD.

00B3

D1

POP D

00B4

El

POP H

00B5

FI

POP PSW

00B6

C9

RET

00B7

Cl

STORE

POP B

/THIS SUBROUTINE TAKES INFORMATION

00B8

5E

L00P1

MOV E,M

/FROM MEMORY AND PUSHES IT ONTO THE

00B9

23

INX H

/CB STACK IN TWO-BYTE WORDS. THE NO.

OOBA

56

MOV D,M

/OF BYTE PAIRS PUSHED IS DETERMINED

OOBB

D5

PUSH D

/BY A: POP THE RETURN ADDRESS AND

OOBC

23

INX H

/SAVE IT IN BC, MOVE BYTE ADDRESSED

OOBD

3D

DCR A

/BY HL INTO E, INCREMENT HL AND PUT

OOBE

C2

B8

00

JNZ L00P1

/SECOND BYTE INTO D; PUSH DE , INCREMENT

00C1

C5

PUSH B

/HL, DECREMENT A AND CHECK FOR ZERO;

00C2

C9

RET

/IF ZERO PUSH RETURN ADDRESS AND

/RETURN.

00C3

Cl

RETRV

POP B

/THIS SUBROUTINE POPS TWO-BYTE WORDS

00C4

D1

LOOP 3

POP D

/FROM CB STACK AND RETURNS THEM TO MEMORY.

00 C 5

72

MOV M,D

/NO. OF BYTE PAIRS IS DETERMINED BY A:

OOC6

2B

DCX H

/SAVE RETURN ADDRESS IN BC , THEN POP

00C7

73

MOV M,E

/FIRST BYTE PAIR INTO DE ; MOVE BYTE IN D

00C8

2B

DCX H

/TO MEMORY LOCATION ADDRESSED BY HL , DE-

00C9

3D

DCR A

CREMENT HL AND MOVE BYTE IN E TO MEMORY;

OOCA

C2

C4

00

JNZ L00P3

/DECREMENT HL AND A ; IF A IS ZERO, PUSH

OOCD

C5

PUSH B

/RETURN ADDRESS AND RETURN.

OOCE

C9

RET

0060

3E

FD

INIT

MVI A ,0FDH

/THIS SUBROUTINE PERFORMS INITIALIZATION:

0062

D3

OA

OUT 10

/OUTPUT MASK WORD TO DISABLE UNWANTED

0064

21

00

01

LXI H ,0100H

/INTERRUPTS (NOTE: THE ACTUAL MASK WORD

0067

36

02

MVI M,02H

/AND OUTPUT PORT ARE SYSTEM DEPENDENT.

0069

23

INX H

/CHECK YOUR SYSTEM MANUAL FOR DETAILS).

006A

36

01

MVI M ,01H

/INITIALIZE MEMORY POINTER AT LOCATION

006C

FB

El

/0100H, LOAD MEMORY POINTER, LOW BYTE

006D

C9

RET

/FIRST, THEN ENABLE INTERRUPTS AND

PSW

EQU 6

/RETURN .

SP

EQU 6

Table 5. Assembly-language programming and machine code for full interrupt service

ister pointing to the CR and the
HL register set to zero. The com-
mand is then executed by the
interpreter. Table 3 shows an
assembly-language simulation
of this. Note that the character
string RUN 6 is stored, and then
a jump is executed to %E442.

This approach has the advan-
tage of being able to process in-
terrupts in BASIC with only a
limited requirement for assem-
bly-language programming. The
disadvantage is that a program
executing at the time of inter-
rupt cannot be continued. This
can severely limit what can be
accomplished if the time be-
tween interrupts is short. Since
our situation demanded a 15
second cycle, we had to keep
trying.

Full Interrupt Handling
in BASIC

Our final approach permits
full interrupt processing in
BASIC. A BASIC routine may be
interrupted at any point (in-
cluding within FOR/NEXT
loops), and the interrupt is ser-
viced in a BASIC subroutine.
When the service is finished, ex-
ecution continues at the point of
interrupt. Furthermore, the
basic interrupt service itself
may be interrupted, which pro-
vides a great deal of flexibility in
programming.

This is the most practical ap-
proach for our application, but it
requires a more extensive
knowledge of the interpreter
and requires the most memory
to execute. If we wish to inter-
rupt a BASIC program, execute
another BASIC program and
then return to the point of inter-
rupt, we must save the contents
of all of the registers as in the
previous example (eight bytes).
We must also save all of the per-
tinent interpreter control
variables (30 bytes) and that por-
tion of the command string
stored at %0269 that will be
written over by the RUN 6 com-
mand and the trailing CR and
%FF (eight bytes). Note that on-
ly seven bytes of the command
string actually need to be saved
if only a single digit-page
number is used in the RUN com-
mand. However, it is recom-
mended that the program be
written to save eight bytes of the

string since that will cover the
highly probable situation where
a double-digit page number
might be used.

The most convenient way to
store the information to be
saved is to use the CB stack
pointer and push the informa-
tion onto the stack. This will lim-
it the number of times that an in-

terrupt service can itself be in-
terrupted, since 46 bytes of in-
formation must be saved, yet
only 200 bytes of stack space
are provided by CB. However, if
the interrupt service does not in-
clude a lot of nested CALLS or
GOSUBs, the limitation is not a
problem.

The BASIC programming

necessary to service interrupts
is shown in Table 4. The diagram
in Fig. 3 shows the relationship
between the BASIC program-
ming and the assembly-lan-
guage programming shown in
Table 5. The program on
memory page 4 can be anything,
including a routine to load the
machine code as in the previous

Microcomputing January 1980 183

example. The sequence is
started by executing a call to the
subroutine ‘INIT’, shown in
Table 5, which enables the inter-
rupts and initializes the memory
pointer, which is discussed in
the next paragraph (in this case,
‘INIT’ is located at %0060). The
interrupt handler on memory
page 6 must end with a call to
the subroutine ‘REPL’, also
shown in Table 5, which in this
example is located at %0096.
Anything after the CALL %0096
will not be executed since the
subroutine ‘REPL’ moves the
stack pointer and loses (on pur-
pose) the return address.

The assembly-language sub-
routine ‘LOAD’ and the string
‘STR’ are the same as in Table 3

and therefore not shown, but the
subroutines ‘SAVE’ and ‘REPL’
have been added, and the sub-
routine ‘INIT’ has been extend-
ed. The address of the jump
command at %0008 has been
changed so that interrupt ser-
vice will start with the SAVE rou-
tine, which pushes the register
contents, program variables and
part of the existing command
onto the stack. It then uses a
memory pointer, initialized by
‘INIT’, to determine where to
store the stack-pointer address.
The memory pointer allows the
program to keep track of more
than one stack pointer address
in case the interrupt service is
interrupted before it is finished.
It always points to the location

in memory where the next stack-
pointer address is going to be
stored.

The ‘REPL’ routine performs
the reverse of the ‘SAVE’ rou-
tine. It recovers the last stack-
pointer address stored and
moves the CB stack pointer to
begin retrieving the necessary
information. When the RET is
executed, the program that was
executing at the time of inter-
rupt is reentered.

The location of the assembly-
language interrupt service is en-
tirely arbitrary with the excep-
tion that the JMP SAVE com-
mand must be located at the
point to which control is trans-
ferred when an interrupt is re-
ceived (in our case, location

%0008). The interrupt service
can be stored in PROM, pro-
vided that the memory pointer,
which is changed during each
service, is stored in RAM.

Give It a Try

All of the methods of handling
interrupts outlined in this article
have been tested and proved
satisfactory. Any of the three
can provide a new dimension to
your real-time programming if
you are willing to take the time
to understand your interpreter.
So if you think your application
requires it, give it a try. All you
need is a source listing for your
interpreter and the information
in this article. It is well worth the
effort.*

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cabinet, cables to PET and DAA, full documentation and
software.

(The Net Works is now)

TNW

^T56

Corporation

Ask your dealer or contact —

ASTRONICS • (714) 278-5441
335 1 Hancock St. • San Diego CA 92 1 1 0

(CLOSE OUT

KIM BUS
8K RAM

The famous HDE 8K RAM
now on sale at the incredible
price of SI 55.00-quantity
one. Two or more-$1 50.00.
Hurry while supply lasts.

THE
LOGIC
. STORE

P.O. Box 1712, Auburn AL 36830
Call Toll Free 1-800-633-8724
regular phone number (205] 745-7735

is L25

WE WILL NOT BE
UNDERSOLD!!!

Find the best price you can in this
magazine on a box of 10, 5 Vi” Verbatim
diskettes and

i

Subtract

50c

(Low discount pries- $26.50)

THAT’S OUR PRICE

FUpfks

Eijfa

Sfmaga ^aioi

4636 Park Granada
Calabasas Callfoi
91302 f 2131 992-1

‘Offer good ’ till December 31, 1979, as
long as supply lasts. Price includes
shipping in the US except for Alaska &
Hawaii.

184 Microcomputing January 1980

WE SELL a complete package of
programs, detailed instructions,
custom forms and program manu-
als.

YOU SELL computer billing and
record keeping to organizations
conducting “Jog-a-thons.” Your
competition sells at 20% to 25% of
gross receipts. You can do a better
job for less and make excellent
profits.

THE JOG-A-THON 80/8 SYSTEM

■ Disk programs, manuals,

forms $229.00

■ Manual (cost deductible on

system purchase) $ 29.00

■ Write or call for full details

SYSTEM REQUIREMENTS — A
TRS-80 (32K/Dual Drives) or the
H-8 (40K/Dual Drives) plus a 132
column printer.

3667 MONTALVO WAY
SANTA BARBARA, CA 93105
TELEPHONE (805) 682-L270

FOR THE STAMP
COLLECTOR

■ The ideal tool for philatelists with medium
to large collections.

■ Special attention given to make data entry
and corrections fast and easy. Keeps your
information current and accurate.

■ Screens your collection for any single, or
group of, characteristics.

■ Provides a variety of pre-designed and
user selected reports to CRT or printer
Reports are sorted on any combination of
stamp characteristics. A report of catalog
numbers not in collection also included

■ One thousand stamps per Data disk with
Multi-disk processing for the large collec-
tion. Summary data on totals per country,
value, or special categories included in
Multi-disk capabilities.

SYSTEM REQUIREMENTS - A

TRS-80 (32K/Dual Disks), or H-8 (40K/Du-

al Disks-MBasic) and printer (64 or more

characters/line)

STAMPS 80/8 $34.95

©1979 Ithaca Intersystems Inc.

5-10 times faster...
and more!

Meet Pascal/Z,™ the fast, flexible compiler with
higher speed, greater efficiency and improved debugging:

■ True Z-80 native code Pascal compiler — 5-10X faster
than competing P-code implementations — no interpreter
required.

m The only multi-tasking Pascal — produces ROMable
re-entrant code.

■ Optimized for fastest execution — recognizes and
exploits special cases.

■ Easily transportable — all hooks to your system made
through support library.

■ Includes IEEE standard floating point package.

Single copy on CP/M-compatible disk includes compiler,
companion macro-assembler & source of the library, $275.
OEM licenses available. Write or call for more information.

OoDteo% 7 steooos

Ithaca Intersystems Inc., 1650 Hanshaw Road/PO Box 91,

Ithaca, NY 14850/607-257-0190/TWX: 510255 4346

introducing.

MAYDAY

The Uninterruptable Power Supply

Mr. Bytes lost his program due to power failure.
Don't lose yours - Protect your time and investment.

For price list and detailed specifications, contact your nearest Sun-Technology
distributor or call direct to:

//Pirn - £fec/mo/o<w, $ nc . ^ S126

Box 210

New Durham, New Hampshire 03855 (603) 859-71 10

(Manufacturing high technology products since 1970)

Reader Service— see page 227

Microcomputing January 1980 185

SUPPORTING

6800

COMPUTERS

■£ '*■* i jp : -

f 1 MS

High Perfcxmance Cassette Interface

• FAST - 4800 Baud Loads 4K in 8 Seconds!

• RELIABLE - Error Rate Less Than 1 in 10® Bytes.

• CONVENIENT - Plugs Directly Into The SWTPC.

• PLUS - A Fully Buffered 8 Bit Output Port Provided.

• LOW COST - $49.95 For Complete Kit.

• OPTIONAL - CFM/3 File Manager.

Manual & Listing $19.95
(For Cassette Add) $ 6.95

TERMS: CASH, MC or VISA; Shipping & Handling $2.00

JPC PRODUCTS CO. ...

P.O. Box 5615, Albuquerque, N. M. 87185
Order Phone (505) 2944623

6809 !

MD-690b Single Board Computer

$299 Assembled
$239 Kity^

./Vv

• IK RAM

• 10K PROM space

• Parallel keyboard input A

• Memory-mapped video firmware 9

• Fully S-1 00 compatible
(including 8080 type I/O)

• MONBUG II monitor included 9 * <3

• 2400 baud cassette interface f ^

• 20 I/O lines

• RS-232 level shifters •

• Real time clock f <£$

• DMA , ,0-

• 6809 jfyfp

From time to time Kilobaud Microcomputing makes its
subscriber lists available to carefully-screened companies and
organizations whose products, services or information may be of in-
terest to you. In every case, we must approve all organizations wishing to
mail to our subscribers. In every case they receive a list of names and ad-
dresses only— no other information we may have is divulged. Each organiza-
tion may use the list only once and agrees never to make any personal or
telephone solicitations from it.

The overwhelming majority of our subscribers appreciate this controlled
use of our mailing lists — it helps them shop conveniently by mail for products and
services they need, often at substantial savings. A few people prefer their names not
be used. It is to them we address this message.

If you do not wish to be a part of this service, please complete the form
below . . . your name will not be used in this manner for any reason.

(If you asked us in the past to remove your name from our lists, there is no
need to repeat the request.) Please allow about six weeks for your request to take ef-
fect.

□ I wish to have my name removed from the list of subscribers receiving mail other
than the regular subscription to Kilobaud Microcomputing.

Mr.
Mrs.
Send to: Ms. _

Please Print

Address
City

_State_

Zip.

Mail this form with your mailing label from the latest issue (or fill out the Information
as it appears on the label) to:-

Kilobaud Microcomputing
Subscription Services Dept.

P.O. Box 997
_ Farmingdale NY 11737

ATTENTION TRS-80* OWNERS

At last! An attractive home for all of the parts of
your system— keyboard, video display, power
supply, and, last but not least, the cassette. The
TRS-80* performs as a computer— Now it can
look like

Classic black and silver color scheme to match
your TRS-80*. Now your system can be portable
without dismantling. The cassette recorder can
easily be used along side the case and then con-
veniently stored in the side opening without dis-
connecting.

Send check or money order for $69.50 plus $5.00
for shipping to:

Michigan residents add 4% sales
tax.) Visa and MC accepted with
signature, exp. date, and number.

*TRS-80 is a Product of Radio Shack

edianco

Dept. 1A "

P.O. Box 307
Union MI 49130
61 6-64 1 -5956 ^ D47

186 Microcomputing January 1980

Ohio

scientific

just released . . .

Problem Solver: Makes complex decisions based
on your criteria. You can’t be
without it.

Cash Flo: Every item can have a six-point
growth curve — All other cash flow
packages are now obsolete.
Numerology: At last. SPD makes this accurate
tool of the occult available to you.

(Source book $10)

The Tool Box: Modules in a series of tools for
specific business problems . . .
Real Pak 1: Real estate investment property anal-
ysis. Built for pros. Gives you the
“hammer” in any deal.

Baccus 1:MDMS compatible or stand alone invoic-
ing and order entry module. We can’t be
without it.

$30 Disk $ 15 Tape (limited versions)
Specify 8" or 5", Cl or C2. Or, Send $2 for full-line
documentation package

STRUCTURED PROGRAM DESIGNERS
371 Broome St., NY, NY 10013

*>S128

— Professional —

Real Estate Programs

available on cassette or diskette

for Apple & TRS-80 II

Property Management System

• Rental Income Tracking

• Complete Expense Analysis

System w/Manual $125.00
Manual $10.00

Program Modules:

1) Home Purchase Analysis

2) Income Property Cashflow/ Leverage

3) Construction Cost / Profit

4) Tax Deferred Exchange

5) APR Loan Analysis

Price Per Module $20.00
Add $5.00 for Programs
on Diskette

At Computer Stores
™ everywhere or call
ompany (213) 372-9419

for C.O.D. ^*33

2045 Manhattan Ave., Hermosa Beach, CA 90254

SAVE $.

Pre-Holiday Special
Dual Disk DrivesI.Quad Disk Drives!

IN ONE CASE!

One switch, one cord. • Over 400 K* in one (QUAD)Cabinet.

★Dual Drives $698.00 Includes Cable & TRS D.O.S.
★Quad Drives $1359.00 Includes Cable & TRS D.O.S.

ii ■ You would pay $1,000.00 or $2,000.00 at Radio Shacks PriVog

90 Day EXCHANGE GUARANTEE

DEALER INQUIRIES INVITED *A11 drives will access 40 tracks when

Send for our NEW FALL/WINTER CATA- with

LOG. Ask about our LOW PRICES on 77 NEWDOS or NEWDOS+ (EXTRA)

Track Drives, .us LEV E L |V PRODUCTS, INC. ° UTS 'T™ 5 CALL:

32238 Schoolcraft, Suite F4 Livonia Michigan 48154 (313) 525-6200
1 1 AM. to 7 P.M. Tuesday - Saturday

iS Reader Service— see page 227

Microcomputing January 1980 187

NEW SOFTWARE

Edited by Dennis Brisson

The SOFTRAN translator program.

TRS-80 Utility Package

MLUP-l (Machine-Language
Utility Package No. 1) is a single
cassette containing six new ma-
chine-language routines for
TRS-80s that use TRSDOS 2.1 or
2.2, Apparat’s NEWDOS or a
cassette recorder. Three identical !
versions of the package — 16K, \
32K and 48K— are contained on
one cassette. It is programmed
for both TRS-80 Level II and
Disk BASIC. Hardware require-
ments include at least 16K of
RAM.

MLUP-l eliminates keybounce,
performs a formatted input rou-
tine, permits upward and down-
ward scrolling and provides con-
venient insert and delete options.
The keyboard debounce/repeat
gives the user an auto-repeat op- >
tion and lets him ignore the
BREAK key, if he wants to. The
input routine establishes a pro-
tected input field on the video

screen and lets the user specify
field length and location, numer-
ic or string input mode and re-,
duces GIGO because the numeric
mode ignores everything except
valid numeric characters. Price is
$25.

Disco-Tech, PO Box 11129,
Santa Rosa CA 95406. Reader
Service number D69.

Translator Program

SOFTRAN, a translator pro-
gram from Percom Data Com-
pany, 211 N. Kirby, Garland TX
75042, converts files on soft-sec-
tored minidiskettes for use with
Percom LFD-400 hard-sectored
minidisk drive systems. The pro-
gram is available for mini FLEX,
FLEX 2.0 and SSB DOS.

SOFTRAN makes the LFD-400
a universal minidisk storage sys-
tem; minidiskette programs from
all of the principal 6800 software

suppliers may be used with the
LFD-400. It copies soft-sectored
minidiskettes track for track onto
hard-sectored minidiskettes. If
the minidiskette includes a FLEX
or SSB DOS, the DOS is modified
to function with the LFD-400.

Translation of mini FLEX and
SSB DOS minidiskettes results in
more than 10 percent additional
storage space becoming available
than required for the soft-sec-
tored version. Price is $24.95.
Reader Service number P83.

CHECKBOOK II From

Personal Checking The Bottom Shelf

Account Manager Atlanta GA

This program provides the TRS-80 user with the necessary functions*
to interact with today’s sometimes frustrating banking system.
CHECKBOOK II loads using the SYSTEM command into a 16K or
32K tape-based system or 32K or greater disk-based system. The 16K
tape system allows up to 75 transactions in memory at once; the 32K al-
lows 350; while the 32K disk allows 150 with DOS. The user is initially
prompted with the program’s ten -option main menu:

1. Keyboard Input

2. List and Edit

3. Print with Balance

4. Search and Total

5. Reconcile

6. Sort

7. Input from Tape (or Disk)

8. Output to Tape (or Disk)

9. Check File Length

10. Clear (and Kill on Disk)

The first option is used for entry of check data. Each entry has five
fields: five digits for check numbers, six digits for the date, sixteen
characters for a description, seven digits for amount and four addi-
tional characters to code each transaction by type. Input of checks does
not have to be in order by check number; checks are automatically
sorted by check number upon completion of keyboard input.

Listing the data gives the user a chance to review the figures from any
point in the file as well as edit out any mistakes. Edit mode allows
modification of individual fields or deletion of entire records.

Once the user is satisfied that the information is correct, he may
select the Print with Balance option. The user is prompted for the
number of the first check to be displayed and the balance of the ac-
count. This balance need only be entered the first time the program is
used; the balance is automatically updated and recalled during subse-

quent sessions. The screen listing given by this module provides the
balance as a result of each withdrawal and deposit beginning with the
check number specified. Thus, the user can clearly see just where the
account went into the negatives.

Option 4 gives the user the ability to locate all checks with common
fields, for example, to total all the checks made out to the same person
or recall all checks for the same commodity (indicated by the four
character type code). My only complaint is the inability to search by a
given amount. For instance, to recall the purpose of that $48 check you
wrote last July, you would have to scan the records manually for checks
written in that time period and for that amount.

Options 7, 8 and 9 are the file-manipulation options for either disk-
or cassette-based systems. Files are stored with titles indicating the
check numbers contained in that particular file. CHECK FILE
LENGTH tells the user how many more transactions can be added to
the current file.

RECONCILE is the final operation during a session with the
CHECKBOOK. In this module the user is prompted to indicate cleared
checks; the program then checks the balance against the bank’s
monthly statement, lists outstanding checks and permanently removes
cleared checks from the active file. SORT will be used if the entries are
out of order.

Finally, at any point in the program that the user is being prompted
for an alphanumeric input, pressing P will send whatever is on the
screen to the user’s printer. Make sure that the printer is connected
before you try this, as all will be lost if nothing is on the printer port.

CHECKBOOK II has more than its versatile features going for it; the
program flow during an operating session is logically structured, and
errors are correctable before the user gets too deeply in trouble. The
graphics listings are very readable, using a column format perfect for
permanent records. Instead of restricting the user to one particular se-
quence, this program allows the user to act freely, making CHECK-
BOOK II the best of its kind so far and a valuable tool for use in per-
sonal banking.

Kevin Cohan
Micro Lab, ISI

188 Microcomputing January 1980

Heath CP/M

The basic CP/M package for
the Heathkit H 17 and H89 disk
system includes text editor, as-
sembler, debugger and other sys-
tem utilities plus six users’ man-
uals. It operates directly with sys-
tems configured for HDOS. Most
programs designed to run under
CP/M will be available to operate
with this system, including Mi-
crosoft BASIC, FORTRAN and
COBOL. Price is $145.

Lifeboat Associates, 2248
Broadway, New York NY 10024.

Software

Math Library I: This 22-pro-
gram package, written in Level II

BASIC (TRS-80) and Release 4
BASIC (North Star), contains
elementary methods for solving
scientific problems. Suitable for
educators, engineers, consultants
and other professionals who want
to apply microcomputers in solv-
ing real-world problems. TRS-80
disk (DOS 2.1) is $35; North Star
disk (single density) is $45. Dr.
Lee, 5819 Thomas Ave., Phila-
delphia PA 19143. Reader Ser-
vice number L3.

Textwriter: Text-formatting
program to print personalized
form letters, reports and man-
uals, contracts and specifications
or books and articles. Available
for $125 on all commonly used
floppy disk media in versions for
use with CP/M and other similar
systems. Organic Software, 1492
Windsor Way, Livermore CA
94550. Reader Service number
014.

Individual Study Center: Self-
teaching educational course with
subject matter for grade-school
or high-school students (Puzzler,
House on Fire, Around the Ball
Park), as well as for adults who
want to review history, French,
spelling or novice ham license,
etc. The four-cassette packette
for the TRS-80 Level II or Apple
II costs $39.94, plus $1.50 post-
age and handling. TYC Software,
40 Stuyvesant Manor, Geneseo
NY 14454. Reader Service num-
ber T69.

Tax-Deferred Exchange Model:

Shows the total financial im-
pact-considering appreciation,
depreciation, legal fees, im-
provements, mortgages, etc.— of
a tax-deferred or partially tax-
deferred property exchange.
Cassette is $20 and diskette is $25
for the Apple II and TRS-80
Level II. Realty Software Com-

pany, 2045 Manhattan Ave.,
Hermosa Beach CA 90254.
Reader Service number R33.

TIS Software: Three new soft-
ware packages for the Commo-
dore PET/CBM:

Checkbook program— assists in
balancing a checkbook, selects
and displays checks by person,
purpose or date and sums checks
by category or person.

Accounts program — creates a
data base for company names,
addresses, invoice and purchase
order numbers and amounts of
purchase.

Calendar program— enables you
to keep track of appointments in
the office, schedule social en-
gagements, etc.

Each cassette costs $9.90; floppy
disk is $12.95. Total Information
Services, PO Box 921, Los
Alamos NM 87544. Reader Ser-
vice number T75.

Some Dos and Don’ts
for writers and wirers.

Do write about business and educational applications.

We’d like to see more articles on
the use of microcomputers in busi-
ness applications. If you have a use-
ful piece of business software, by
all means write it up for Kilobaud
Microcomputing. There’s also a
need for reviews of business sys-
tems. Businessmen want to know
which hardware items work well

together — with a minimum of has-
sle — and what a computer can do
for them.

Educational programs are going
to be BIG. If your kids are happily
learning math, spelling or any other
subject with the aid of your micro,
please share your programs with
the rest of us.

Do write in English — not
computerese.

One thing: Please try hard to use
as few buzzwords as possible. Re-
member that Kilobaud Microcom-
puting is trying to bootstrap new-
comers into this field, not scare
them away. If you understand your
subject, you shouldn’t have to be
obscure.

Do send a manuscript —
not an illegible printout.

Use regular typing paper (not
the erasable type) and double-space
your manuscript, leaving wide
margins. Number the pages when
you put your name on each page.
Do not type titles, subtitles or text
in all capitals. Manuscripts that are
single-spaced and/or typed in all
caps will automatically be returned
for revision. Underlining a word
indicates that it is to be in italics.
Keep a carbon copy . . . just in
case. Send us the original. Each
page of typed copy will be equal to
about one-sixth of a page in Kilo-
baud Microcomputing.

Do stick to the point;
don’t throw in extrane-
ous, irrelevant material.

Generating an outline of your
proposed article is perhaps one of
the most important steps you can
take (as well as, of course, sticking
to it and not getting sidetracked).

Use active rather than
passive voice. “I fastened the nut”
is better than “the nut was fas-
tened.” Write in short, concise sen-
tences, starting a new paragraph
with each new thought.

Avoid unneccesary abbrevia-
tions and capitalizations. Use sub-
headings for each new section to
provide signposts for the readers.

Don’t make it look like a
PhD thesis.

Avoid footnotes, if possible, and
just put your references in the text
(it’s easier to read that way). And
don’t forget to give credit when
you borrow an idea from someone
else. This is important both ethi-
cally and legally.

Don’t solder in the bathtub.

Do keep figures and text separate.

Put all drawings on separate
sheets of paper — never in the text.
We have excellent draftsmen who
redraw all diagrams and schemat-
ics, so be sure that your sketches
are complete, neat and readable.
Put parts values on the schematic
rather than in a separate parts list.
Use terms “IC1,”“R1” and “C2,”
etc., only if you are referring to
them in the text. If a block diagram

will be helpful in getting the “big
picture,” then by all means include
one. Label all drawings as Fig. 1,
Fig. 2 and so on. Be sure to sequen- »
tially reference figures in the text.
Write a caption for each and in-
clude this with the article text so
our typesetters will be able to set
the type. Put your name and page
number on every sheet of paper
you submit.

Don’t submit programs scrawled in crayon on grocery
bags.

Important: All programs submitted to Kilobaud Microcomputing
must be in a camera-ready condition. This means that programs
should be a printout (single-spaced) and not typed. If you don’t
have a printer, borrow one. Programs may be typed as a last resort,
but they must be single-spaced and legible. (Type carefully to
avoid having to make corrections; use a carbon, rather than a fab-
ric, ribbon.) Don’t print programs on newsprint, colored paper or
lined paper. Use white paper only.

Reader Service— see page 227

Microcomputing January 1980 189

WE WILL NOT BE
UNDERSOLD!!!

Find the best price you can in this
magazine on a box of 10, 5%” Verbatim
diskettes and

(Low discount price -$26.50)

THAT’S OUR PRICE

fHpfta
Egis
Storage

4636 Park Granada

^A101

159

Calabasas California
— 3J992

91302

12133

* Offer good ’till December 31, 1979, as
long as supply lasts. Price includes
shipping in the US except for Alaska &
Hawaii.

Yes!

You Can Have
Your PET™ And
Counter Too.

D£r R 2nd- Cassette System

FEATURES:

• Sanyo Recorder M2545A.

• Digital Counter.

• Audio Location of Programs.

tuing feature allows you to Audibly locate programs at last forward
speeds.

• Includes Interface Module and all Plugs & Cables.

• $83.00 Check or Money Order
Add S3.00 For Shipping And Handling. Canada (U.S. Funds)
$6.00 S & H. Michigan 4% Tax

A DEALERS WRITE

Personal Computer System
. ATARI 800 $895.00

AIAKI Disc Drive 8- Printer Available

Write for more information anrl prices.

CREATIVE SYSTEMS
P.O. BOX402K is 07i
ST. CLAIR SHORES, Ml
48080 .

[apple computer

OR

TGCflS INSTRUMENTS

99/4 HOME COMPUTER

FOR

$ 999 .

INTEGRAL DATA

IP-440 Paper Tiger, List $995 $895

Apple Disk II w/controller $520

DC Hayes Modem $335

^Y3

VOUfi own COfTlPUTER

LTD.

10678 CAMPUS WAY SOUTH
LARGO, MD 20870 - (301) 350-6680

22 MHz MONITORS!

NEW

12 INCH

V W graphics

IF QUALITY

SOLID STATE 22 MHz MONITORS: OEM tabletop style.
B&W P4 CRT, Accepts separate video and TTL level horiz. &
vert, syncs. Any sweep 10-20 KHz. 110 VAC. Simple TRS-80
hookup. Supurb resolution, bandwidth 10 Hz-22 MHz. With full
maint. manual, timing, schematics. TRS-80 hookup, parts lists.
Used, fully checked, very clean, no burns $77. New. checked . $99

TOUCHTONE DECODERS: Telaris/Collins 7640-01. single
12V DIP contains complete analog filtering. Collins digital counter
type 16 tone decoder. Hook up to 12V & 3.58 MHz color burst xtal,
run audio in, get 2 of 8 or 4-bit hex out. Current OEM list price is
$125. Brand new w/crystal & full manual $66

S-100 CORE SALE: Brand new, tested Ampex core. See
article 'ITS TIME FOR CORE" (9/79 Kilobaud p 34) which
describes a simple interface between this core and an S-100
machine. But ignore the prices in the article! Sale priced, including
documentation pkg. and schematics 16K S230 8K $99

AMPEX 29 MEGABYTE DISK DRIVES: Brand new
commercial 20 surface disk drives at a fraction of their OEM cost.
Model DM312, full size console type units. 2.5 MHz data rate with
the best written technical manual we've ever seen If you enjoy
interface design this is the bargain you've been waiting for . $1600

TERMS: UPS included except DM3l2s. SASE or call for full spec
sheets on any item. UPS COD welcome, add $1.25. VISA & MC
t- 4%. NJ add sales tax. Everything guaranteed. Immediate
shipment or immediate refund Phone orders and questions are
welcome.

ELECTRAVALUE INDUSTRIAL

P.O. BOX 157-K p.

MORRIS PLAINS, NJ 07950

Phone orders
are welcome

201/267-1117

Datapoint CRT Terminals

Fully-Assembled — Guaranteed

#3360 $649.50

• Add $15 packing. refurbished

• Shipped FOB Washington, D C. Terms check, M.O.
or charge.

• 90-day guarantee • Scrolling version $695.00

Model 3360 speeds from 300-4800 Baud, numeric
keypad, cursor controls, Edit. Block-Transmit, search
modes. ASCII Keyboard with codeable options.
Green phosphor, 24 80 ch lines, addressable cursor:
RS-232C serial interface; other speeds available.
Manual $10; cable kit $9.95. Datashare/IB.M-2260
compatible version $1 .1 00.00. • Model 3000 $495.00.
M-33 ASR Teletype $895, KSR $725; All M-28. 35
components available, also Modems, readers.
OUANTITY DISCOUNTS AVAILABLE. Leasing, ser-
vice at low prices.

TELECOMMUNICATIONS SERVICES CO.

Box 4117, Alexandria, Va. 22303 ^»J26

703-683-4019 / TLX 89-623

We offer for the Micropolis Mod 11

Accounts Receivable

$ 1 50.00

Accounts Payable

1 50.00

General Ledger

1 50.00

Investment Package

35.00

Assembly Language Course

35.00

Family Package

30.00

Tiny Pascal

45.00

We offer for the TRS-80 Level II on tape

Tiny Pascal

45.00

Assembly Language Course

35.00

Family Package

30.00

(Illinois Residents add 5% sales Tax)

lAil

i^S95

813 Mac Arthur Drive

Urbana, II. 61801

217-367-7806

d

Considering a computerized
Christmas?

Then go for 0SI!

Isoponl*

Bill

Ei

.'Ilia

THE C4PMF

December Deals

Buy a Challenger IP at $349
or a Challenger 4P at $698
and receive 4K static RAM free!!

($70 value)

Similar savings on other 0SI products

^C171

51591 US 31 N
South Bend IN 46637
(219)277 4655

ggj j]

-ur^i

H9fM>tfihSnPl

MicroPhase Systems

Announces

WORDMASTER for TRS-80s

Let WORDMASTER transform your Model I or Model II
TRS-80 into a high quality word processing system

WORDMASTER features include: full screen

editing, margin justification, line insertion,
line deletion, block move, block copy, find,
change and much much more.

Model II $149.95

req. 1 disk, 64k mem.

Model I disk version $ 99.95

req. 1 disk, 48k mem.

Documentation only $ 9.95

(can be applied to later purchase)

STOCK MARKET DATA TAPES for TRS-80 Model I I !

Each tape cassette contains one months data for
the NYSE or AMEX stock of your choice. Data
includes daily high, low, close, and volume
information. Can be read by any Level II Basic
program with simple input statements. Available
for Jan. 1979 to present. Please specify month
and stock name.

one months data $ 5.95

charting program $49.95

(plots high, low, close and 2 moving avgs.)

MicroPhase Systems
11223 E. 45 St. So. #314 ^M125

Tulsa, 0k. 74145

TRS-80 has a HOME

Custom furniture for the
TRS-80 off ice or home decor.

Featuring

• Custom all wood, hand rubbed, walnut finish.
•Builds-in complete TRS~80 business system.

• Provides copy shelf, drawer, and cushion arm rest.

• FOR 24 HOUR INFORMATION

PHONE 408-946-1265

/VS

*^A115

AUDIO -VIDEO 248S AUTUMNVALi AVI.
SYSTEMS SAN JOSS, CA. 95132

190 Microcomputing January 1980

Mi crocomputer Systems Division

NEECO PROUDLY ANNOUNCES THE NEWEST

HARDWARE AND SOFTWARE FOR YOUR PET!

The PET is now a truly sophisticated
Business System with the announcement
of these peripherals and software packages.

i

EEK

I

PRODUCT

DESCRIPTION

PRICE AVAILABILITY

PET 2001— 8KN ( Large Keys) 8K RAM
PET 2001 — 8K 8K RAM

PET 2001— 16KN (Large Keys)l6K RAM*
PET 2001— 32KN (Large Keys)32K RAM

PET 2023 PRINTER
PET 2022 PRINTER
ROMRETRO KIT
PET 2040
PET C2N

$ 795
$ 795
$ 995
$1295
$ 850
$ 995
$ 90
$1295
$ 100

IMMEDIATE

IMMEDIATE

IMMEDIATE

IMMEDIATE

IMMEDIATE

IMMEDIATE

IMMEDIATE

IMMEDIATE

IMMEDIATE

ROLL FEED
TRACTOR/ROLL
UPDATED O/S
DUAL FLOPPY*

2nd Cassette

'The 16K/32K (large keyboard) units do not include a cassette drive. Order C2N Cassette.
2040 Floppy Drive requires a 16K or 32K unit. 8K RAM Retrofit available July.

ALL PETS ARE FULLY TESTED BY NEECO BEFORE SHIPMENT. NEECO IS A
FULL CUSTOMER-ORIENTED BUSINESS. CALL FOR OUR FREE CATALOG
SEND US A COPY OF THIS AD WITH AN ORDER AND WE WILL WARRANTEE
YOUR COMMODORE PET FOR ONE FULL YEAR!

PET-DISK BASED BUSINESS SOFTWARE

SOFTWARE/APPUCA TION

REQUIRES

AUTHOR

AVAILABILITY

PRICE

WORDPRO II / WORD PROCESSING

2040 + 16K PET

PRO/MICRO

IMMEDIATE

$100

WORDPRO III / WORD PROCESSING

2040 + 32K PET

PRO/MICRO

DECEMBER

$200

GENERAL LEDGER

2040 + 32K PET

CMS SOFTWARE

IMMEDIATE

$295*

ACCOUNTS PAYABLE

2040 + 32K PET

CMS SOFTWARE

DECEMBER

$295-

ACCOUNTS RECEIVABLE

2040 + 32K PET

CMS SOFTWARE

DECEMBER

$295*

MAILING LIST

2040 + 32K PET

CMS SOFTWARE

IMMEDIATE

$100

NEECOLEDGER

COMPUTHINK .4
M DRIVE + 32K PET

NEECO

IMMEDIATE

$795

NEECOMAILER

COMPUTHINK .4
M DRIVE + 32K PET

NEECO

IMMEDIATE

$150

*The CMS Software (G/L, A/R, A/P) are based on Osborne & Associates trial tested business basic software.
Software is complete with full documentation and user instructions. All packages require a printer for output.
Commodore recommends the NEC Spinwriter (available from NEECO) as the output printer for WORDPRO.

DEALER INQUIRIES INVITED ON SOFTWARE & NEC (PET) SPINWRITER

FOR WORD PROCESSING
NEC IS BEST!

55 characters per second output speed
Changeable thimble for different typestyles
Less than 1% warranty malfunction rate
IBM quality letter output
Dealer inquiries invited

THE NEC SPINWRITER
MODEL 5530-P ( SS™

$2995

*Price includes IEEE interface
to PET. IEEE Port is available
for use with 2040 Dual Disk.

*The NEC 5530-P is the output printer recommended by Commodore for their Word Processing System.

^N12

NEECO

NEW ENGLAND ELECTRONICS CO.. INC.

679 HIGHLAND AVE., NEEDHAM, MASS. 02194
SHOWROOM HRS.: MON. - FRI. 9:30 - 5:30, EST.

( 617 ) 449-1760

MASTERCHARGE OR VISA ACCEPTED
TELEX NUMBER 951021, NEECO

Microcomputer Systems Division

iS Reader Service— see page 227

Microcomputing January 1980 191

CAT-100 GETS

COLOR!

Complete on two S-100 boards,
CAT- 100 is the original 16-color
imaging system with high
resolution video frame grabber.

FREE CATALOG stock .

request yours today

Video out: 4-bit D/A
16 levels or 16 colors

3 RGB color outputs '
Phototrigger -

72 HR. SHIPMENT

Video input: fu!! speed Expandable 32K byte
real-time 4-bit A/D | maae memorv

\ Lightpen input 1

Character

\\i Expansion bus /

generator

A —

{yinaSif i

LirtMuiiiiuimiiiJui

IfDIGITAL Dept. 32 595 Matadero Avenue
■VIDEO ^ Palo Alto. CA 94306

I SYSTEMS «^ D6 ° 415/494-6088

TRS-80 NEEDS
FILLED

A TRS-80 is a trademark of Radio Shack, a division of Tandy Corp.

•Disk drives — plug and run
Shugart 35 or MPI 40 track @$3198. Micropolis 77
track @ $570 4-drive cable @ $34 P.P.-5" (bx of 1 0)
disks @ $27.50 P.P.-in hrd. case $31 P.P.

•Printers— Harris Selectric typewriter (refurbished) 8.
cables 8. TRS232 @ $790— new Centronics— 779
tractor @ $950 8. CENT. 730 @ $820— cable for $34
P.P.

Professional business software — mail list 8. Library
100 @ $75— letter secretary or job cost @ $240
ea.— interact inventory control with B.O.M. @ $299
Osborne interact A/R, A/P, 8. G/L @ $350— P/R @
$125— All P.P.

1 Power drops 8. outages? System boot out? Lose data?
— Get Mayday UPS (uninterruptible power supply)
from $195 — write

MA. residents, add 5% tax** P.P. means postpaid
cont. U.S.A., All else F.O.B. Tewksbury* * M/C, VISA,
or check.

OMNITEK SYSTEMS

24 Marcia Jean Dr., Dept. M
Tewksbury MA 01876
iTel. 617-851-3156 1

r/"018

MICROPOLIS

Generalized Accounting Software

The GENERAL LEDGER pro-
vides multiple chart of ac-
counts capability, user de-
fined reporting, multi-level
summarization and many
large mainframe features.
For additional information
on the GENERAL LEDGER
or other accounting soft-
ware, write to:

Management Information Specialists
4823 South 25th Street
Milwaukee, Wisconsin 53221

^M121

#* FR - E& V

SORCERER „„ ^

Z80 Processor
Full-size ASCII Keyboard
Calculator Style Numeric Pad
8K RAM (up to 48K RAM)
Resident 4K Monitor ROM
Interchangeable ROM Pacs

with 8K RAM

Dual Cassette I/O
Serial and Parallel 10
30 x 64 Character Display
240 x 512 Graphics Resolution
64 User Defineable Characters
S-100 Compatable

^ C List Price
$ 995.

Receive FREE Cassette Recorder Value $67

with 16K RAM 1145.

Receive FREE 12” Video Monitor Value $149

with 32K RAM 1295.

Receive FREE Monitor and Recorder Value $216
with 48K RAM 1445.

Receive FREE Monitor and Recorder

PLUS Extended BASIC Value $265

WE PAY ALL SHIPPING AND HANDLING CHARGES.

Shipment stock to 30 days. Connecticut residents please add To sales tax.

198 General Lyon Rd., Eastford, CT 06242

203-974-1214 ^M116

HOW TO START YOUR
OWN SYSTEMS HOUSE

A practical guide for the small EDP entre-
preneur. 213-page manual covers all aspects of
starting and successfully operating a Small
Business Computer company. 5th revised edi-
tion June 1979. From the contents:

• The Systems House Industry • Hardware,
Software or Both? • Market Selection &
Evaluation • Industry Application Opportunities

• Equipment Selection • Becoming a Distributor

• Product Pricing • Getting Your Advertising
Dollars Worth • The Selling Cycle • Financing
For The Customer»Questions You Will Have To
Answer Before The Customer Buys • Solving
The Service Problem • Protecting Your Product

• How To Write A Good Business Plan • Raising
Capital •

Send $36.00 (check, VISA or Mastercharge) to:

Essex Publishing Co., Dept 1
285 Bloomfield Avenue
Caldwell, N.J. 07006 »^E56

Credit card orders: Send card #, date exp. Add
$2.00 for rush, air mail shipping. N.J. residents
add 5% sales tax. For faster shipment on credit
card orders, phone (201) 783-6940.

12” BLACK & WHITE
LOW COST VIDEO
TERMINAL

Easily interfaced with Radio Shack TRS 80

$149.00 LIST

Will sell 6 feet coaxial cable $5.00
Add $5 for shipping and handling in Continental U.S.A.

• Ideal for home, personal and business computer systems;
surveillance monitors • 12" diagonal video monitor • Com-
posite video input • Compatible with many computer
systems • Solid-state circuitry for a stable £ sharp pic-
ture • Video bandwidth— 12 MHz ±3 DB • Input im-
pedance— 75 Ohms • Resolution— 650 lines Minimum IN
Central 80% of CRT; 550 Lines Minimum beyond central 80%
of CRT ref El A RS-375 • Dimensions— 11.375" high; 16.250"
wide; 11.250" deep (exclude video input con-
nector) • Weight— 6.5 KG (14.3 lbs) net

Use Master Charge/Visa or send money order.

Micro Products Unlimited

P.O. Box 1525, Arlington, TX 76010
817/461-8043
Dealer inquiries welcome

v* M81

CI-68A CONTROL INTERFACE

• 8 opto-isolated inputs

• 8 reed relay outputs

• Relay status register

• /IRQ and /NMI jumper
selectable

• Complete
documentation

• $79.95 kit

• $95.00 assembled
and tested

AD-68A ANALOG-TO-DIGITAL CONVERTER

• 8 Analog inputs
(0-2.5v)

• Single ramp, software
driven conversion

• 8 bit; 9.6 ms maximum

• Complete
documentation

• $39.95 assembled
and tested

For SWTPC 6800 type computer. Write for more
information ^ J24

Terms: US and Canada add 5% shipping. Others add
15% US funds only TX residents add 5% tax. VISA and

# JLk _ _ MC ok.

Bjt NNOVAT1V£ ^ ECHNOL(x; Y

510 Oxford Park • Garland. TX 75043 * (214) 270-8393

“ANNOUNCING™

iCOMPUPRISM?

CHECK THIS LITTLE
M U T A l\l T OUT ! ! !

Single board color graphics interface
for s-100 bus systems
16K on board memory \ !

16 colors always available !

27648 individual picture elements •

Every element programmable in any
color at any time !

Sequential memory mapping makes
programming easy !

KIT $240.00 ASSEMBLED $280.00

4 MHz MOD FOR S.D. SYSTEMS
EXPANDORAM $10
16CHANNEL A-D,8 CHANNEL D-A
FOR S-100 BUS* BARE BOARD WITH
DOCUMENTATION $25

<2 J.E.S. GRAPHICS
? P.O. BOX 2752
v TULSA, OK. 74101

HH(918) 742-7104 MB

192 Microcomputing January 1980

(•) rondure company da ^ s !"H!” 3s the computer room

I ^ ^R7

SPECIAL

Printer for your Microcomputer

GE TERMINET
300 PRINTER

DATEL SELECTRIC

(IBM Selectric Mechanism)

Pin feed— 9” paper

• 80 Print positions

• Receive only

• ASCII code

• RS-232 interface

• 30 CPS

• Upper & lowercase

• Shipping wt 75#

Shipping containers $15.00.

(used)

(good working condition)

Will run on serial RS232 port of most
micros including TRS-80.

$450.00

ASCII SELECTRIC

Printer Mechanism: Heavy duty
input/output, Series 745.

Weight: 120 lbs. Dimensions: 29”
H x 35” W x 33” D.

Print Speed (10 characters per
second)

Platen: 15” wide, pin feed or form
feed device optional (132 print
positions).

Parallel output only lOcharacters
per second accepts 7 bit ASCII
parallel w/strobe & prints on
Selectric. The unit still works as a
typewriter in off-line mode.

ASCII Keyboard

(used)

with enclosure

SALE $25.00

$995.00

TESTED WITH
NEW
ASCII

ELECTRONICS

ASCII Selectric with ASCII parallel electronics.

New

RS232 Connectors

I

: Male -3.50
| Female -4.50
\ Covers — 1.75

WE HAVE FLAT-PACK
ACOUSTIC

Modem pickup

$19 50

USED FANS

Muffin — 8.00
Sprite — 4.00

MICRO SWITCH KEYBOARD

USED BUT LOOKS VERY NICE

USED OMNITEK

NEW

CAT

MODEM

195.00

ORIG.

ONLY

95.00

$40.00

(WITH PRINT)

USED

POWER SUPPLY
$15.00

V 5, 16.5, 6,-3
A 12, 6, 2, 1

NEW

\

i'

POWER

SUPPLY

USED Mh

ANS./ORIG.

V 5, 12, -12
A 3, 6, 3

25.00

149.00

ORDERING INFORMATION:

we ship the same day we receive a certified check or money order.
Texas residents add 5% sales tax. Please call if you have a question.
Write for our CATALOG of many parts, terminals, printers, etc.

All items subject to availability. Your money returned if we are out
of stock.

SHIPPING INFORMATION:

Modems: $2.00 each; 2 for $4.00 UPS.

Large Items & Parts: Specify Freight or Air Freight Collect
Foreign Orders: Add appropriate freight or postage.

We now take Master Charge and Visa orders. Specify full number,
bank number and expiration date.

^ Reader Service— see page 227

Microcomputing January 1980 193

USBD
PRINTERS

SUPER “SELECTRIC” ONE _

"Selectnc" Line Printer: Receive Only (no kbd). ASCll-"Centronics - ' Parallel Input,
BIDIRECTIONAL PRINT . Line Storage Buffer, Page Programmable, 8080A CPU,
Dual Pitch' (10 4 12 charsVmch), 15" Carriage. Interlaces with ALL Mini & Micro
Computers. Packed with extras!! OEM Modified 'SELECTRIC'. Worth a fortune!
•Our SELECTRIC ONE' comes with complete data. *980.00

SUPER “SELECTRIC” ONE-A

Same as the ' Selectric One" but also has X-Y Plotter capability, 1/60 of an inch in-
crements. BiOirectional Carrier & Platen, Plotting Applications 15" wide by
approx. 50 pages long. Nothing else like it in the world *1 300.00

CENTRONICS 102A

BiDirectional Line Printer featuring: 9x7 Dot Matrix, Auto Shutoff, 330 characters
per second, 132 columns, Standard Centronics Parallel Input, TRS 80 COM-
PATIBLE . Dual Print Heads. 125 Lines/Minute 4 much more,

Tested and Functional *895.00

I/O “SELECTRIC”

KSR-type with 15" Carriage. IBM Heavy Duty Model 7X5, complete I/O Encoding 6
Decoding (Solenoids 4 Microswitchcsj. Works as a typewriter (shift and index
solenoids need +26 VDC). HI-QUALITY PRINT . Removed from WORD PRO-
CESSORS, takes standard IBM type elements, upper 4 lower housings included.
110 VAC operation. Good condition, includes I/O data 4 info Only *395.00

RECEIVE-ONLY “SELECTRIC”

Bargain-priced IBM Model 1980 R.O. "Selectric" Printers. Upper case, 11” Car-
riage. PINFEED PLATEN (takes teletype paper). Standard Tilt 4 Rotate Encoding-
Standard Solenoid Configuration. NO Keyboard (Receive-Oniy). Takes most
SELECTRIC type elements. Used, as-is, from Airline Reservation Systems. Ideal

for use with TRS-80 level 1 9.00 «a.

Buy 2 and SAVE!! 2/*21 9.95

“TWIX” SELECTRIC

KSR Machine with '‘telex-type" keyboard, telephone line compatible, 1 1” Carriage,
Pinfeed Platen. IBM Model 731 Heavy-Duty Printer. Also includes I/O
“Black Box ' with RS-232 Circuitry and Internal MODEM. Ready toconnoct to the
phone line (includes 4-prong phone plug I/O). As used with ' TELEX" or ' TWIX "to
transmit 4 receive typed messages over phone wires. As-is, removed from Airline
Reservation Systems Made by ICOT. SPECIAL PRICE Only *495.00

PRINTER SOUND HOOD

Built by Gates, the Sound People. 24" wide, 21" long and 12" high. Fits over Sel-
ectric “IN-THE-DESK" type pr.nters like 2741, MT/ST, our I/O SELECTRICS and
others. Quiets printer operation by as much as 30 dB Features hinged Plexiglass
front cover and keyboard door, foam lined, holes for platen knobs. Only slightly
used. Orig. cost over $200.00. Now Only *26.50 •«.

THE FINE PRINT:

• In addition to Printer cost, there's a $1 7.50 charge ($30.00 for the Centronics) lor the ship-
ing crate (the R.O. Selectric Model 1980 and sound hoods require nocrates) We shipall
printers by TRUCK. FOB our warehouse, except Sound Hood & Model 1900 which are
shipped via UPS. whenever possible.

• Payment must be received and collected before we can ship When your Printer arrives,

you must pay lor the delivery “C.O.O.".

• Unless otherwise specified, all Printers are sold on an "as-is , first come, first serve"
basis, though we take great care to insure that each machine is shipped clean,
whole and usable.

• Mastercharge 4/or VISA accepted •Telephone orders welcome!

■IBM Trademark

iA

CFR

Associates, Inc.

Newton, N.H. 03858

(603)382-5179

Write or Call for our Special PRINTER FLYER

p^C160

DELTRONIKS

1. EMM 4200 A, 4K Static RAMs, Ceramic

A local memory boards manufacturer
closed. We bought the new memory
boards and took these 4200A static RAMs
out. They are tested and 90-day
guaranteed 100% good.

Prime tested 4200A 4K RAMs $5.50 ea. f
32/$ 160.00, 300 pieces or more $4.50
ea.

2. Static RAMs MK4104 4KX1 (350 nS)

Ltd.Qty $4.00 ea.

3. Power SCR’s (GEC50A) 100 volt @ I 1 0

amps $6.95 ea.

4. Squirrel Cage Fans (Howard). $7.00 ea.

5. Power Diode 1N1202A, 200 volt @ 1 2

amp 4 for $ 1 .00

6. LM 323 5 Volt 3 amps, voltage regu-
lator 4.95 each or 10/45.00.

7. Super Saver, Micro PD4 1 1 , Ceramic 4K

x 1 dynamic RAMs 8 for $ 1 0.00.

DELTRONIKS

PO BOX 29363 - 028
ATLANTA, GA 30359

Save more than 20%!

AMERICAN SQUARE COMPUTERS

NORTH STAR-INTERTUBE
THINKER TOYS-MICROTEK

The smartest computers at the smartest price.

HORIZON QUAD & DOUBLE DENSITY

LIST

ONLY

HORIZON- 1-32K-D KIT

$1999

$1585

HORIZON-2-32K-D KIT

$2399

$1905

ASSEMBLED & TESTED

$2765

$2195

HORIZON-2-32K KIT QUAD

$2799

$2225

ASSEMBLED & TESTED

$3215

$2555

PASCAL FOR NORTH STAR ON DISK

49

POWERFUL NORTH STAR BASIC

FREE

TEI PT 212 COMPUTER 5 MHz

8000

6250

THINKER TOYS DISCUS/2D A&T

1149

949

DISCUS/2 + 2 1.2 MEGABYTES A&T

1549

1299

MEASUREMENT SYSTEM MEMORY A&T 4 MHz 64K 640

GODBOUT MEMORY

CALL FOR PRICE

INTERTUBE II SMART TERMINAL

S745

MICROTEK PRINTER
ANADEX PRINTER

750

995

675

875

FLORIDA DATA PRINTER 600 CPS 43#OCALL FOR PRICE

Super Software at Reasonable Prices

MARYELLEN WORD PROCESSOR YOUR BEST BUY $38
TEXTWRITER III $125

EZ-80 TUTORIAL- LEARN MACHINE LANGUAGE S25
PDS FOR NORTH STAR - BETTER THAN CP/M $99

COMPILER FOR HORIZON-SECRET SUPERFAST CODE

$100

10% Off Software Prices with Computers

VERBATIM THE BEST DISKETTES BOX OF 10 $29

WHICH COMPUTERS ARE BEST? BROCHURE FREE

NORTH STAR DOCUMENTATION, REFUNDABLE WITH
COMPUTER $20

KIVETT DR
JAMESTOWN NC
27282

(919) 883-1105

P

R

I

N

T

E

R

$

P

R

I

?

R

S

Associates, Inc.

Newton, N.H. 03858

MILESTONE
PRINTER OFFER!!!

^ DIABLO Hytype" Daisy Wheel
KSR TERMINALS

Featuring:

• ASCII RS-232C I/O

• 110,115 & 300 Baud

• 10, 15, & 30 CPS

• Dual 10 & 12 Pitch

• Plotter Capability

• Many more exciting
gPPgpgHHMHHRI features

These used, cleaned and refurbished Daisy Wheel
Terminals feature the FAMED DIABLO “HYTYPE"
Daisy Wheel Printer with its multitude of capabili-
ties. Includes 1/60" horiz. & 1/48” vertical spacing
in the "PLOT" mode.

Limited Offer Special Price

Only $ 1 7 50.00

WHILE THEY LAST!!!

We Also Offer Many
Types of “SELECTRIC”*
Printers: ASR, RO and More.

- For Example: -

Receive only. BCD Coded "Selectric" with Pinfeed Platen
and Data As-is, used. Model 1980

Only *1 09.00 each!!

‘Trademark of International Business Machines

Write or Call for our Special

PRINTER FLYER

(603)382-5179 *^C160

•Mastercharge and VISA accepted
•Phone Orders Are Welcome
•Prices may not include shipping & handling

PRINTERS PRINTERS

••••

tm.

T-BUG USER:

Super TLEGS: Onboard relocator for T-BUG, moves T-BUG to any
desired RAM location. Now examine, modify, # P punch backup
copies of formerly coincident program material, experiment with
parallel kustom T-BUGs. Also will relocate TSTEP.

1 6K Level II Super TLEGS No. LL-0 9.95

TSTEP: Single-stepper for T-BUG. Displays all CPU aspects
related to instruction set as you SPACE through ROM or RAM.
Indispensible for debugging, analyzing alien program material or
learning Z-80.

a) CPU registers in before/after # R like format, user accessible,
independent of T BUG registers.

b) Testable flag status in before/after format.

c) Top stack elements in before/after format.

d) 8 key Implicit Keypad. Backspace, CLEAR, more.

Subroutines can be single stepped or run directly, control
remaining with TSTEP. Also, Super TLEGS will relocate TSTEP,
making monitor and single-stepper into an independently
relocatable unit. Confirm any code by seeing what you are
imagining.

1 6K Level II TSTEP No. LL 1 11.95

EMU 02: Software emulation of the 6502 microprocessor.
T-BUG displays byte, EMU takes it from there. Now you can
write, debug, execute 6502 programs on your TRS-80!

a) Disassembler posts standard 6502 Assembly mnemonic
next to T-BUG displayed byte, in scrolling field.

b) Single-stepper displays 6502 Processor Model in
before/after form, expanded flag and stack elements, all up-
dated after each instruction is SPACE-ed.

c) 4-speed TRACE mode animates 6502 Models, activates
keyboard scan port accessible to 6502 instructions.

d) Fast interpretive RUN mode for realistic execution.

e) 1 3 key Implicit Keypad, Backspace, Relspace, more.

How to have a 6502 without having a 6502! Compare and
contrast, work in a powerful programming language that is
distinct from BASIC, Z-80. Read Apple, PET code.

1 6K Level II EMU 02 No. BL-1 $24.95

.75 mailing each program, CA add 6%

ALLEN GELDER
Box 11721 Main Post Office
San Francisco, CA 941 01

T-BUG, TRS 80 tm Radio Shack/Tandy Corp. ^ G34

194 Microcomputing January 1980

HOBBY WORLD
ELECTRONICS

America’s Largest Mail-Order Computer Store

W;

CALL TOLL FREE:
(800) 423-5387 USA

IN CALIF:

(800) 382-3651

LOCAL 8t OUTSIDE USA
(213) 886-9200

: bbb

MICROPROCESSOR

SUPPORTS

Order by Cat No. 999 and type

TYPE NO.

PRICE

TYPE NO.

PRICE

8212

2.95

Z80A CTC

13.95

8214

4.95

Z80A SI0

55.00

8216

2.60

8224

3.95

6810

5.95

8226

3.95

6820/6520

6.96

8228

5.95

6821

6.95

8238

6.75

6828 .

11.95

8251

6.95

6850

9.95

8253

11.50

6852

6.50

8255

7.95

6860

9.95

8257

15.95

8259

18.95

1822

18.95

8279

9.50

1852

7.50

8271

17.50

1854

13.95

^80A-PI0

13.95

1861

15.95;

1802
6502
6800
8035
8080 A
8085

TMS 9900

12.75

16.50

14.50
6.50

11.75
6.60

15.95

49.00

^verbatim

5 ’A DISKETTES

The most popular diskette in
the world !

S29/box of lO

2 for $55

Cat No. Type Description

1147 525-01 Soft, TRS-80

1148 525-10 10 hole hard,

Apple, North-
star, H8

1149 525-16 16 hole hard,
Micropolis

16K MEMORY
ADD-ON

$75 2 for $140

For TRS-80, Apple, Exidy

Installs in minutes, no special
tools required. Complete with
detailed instructions. Wt 4 oz.
Cat No. Description
1156 For TRS-80 keyboard
unit

1156A TRS-80 without buf-
fered cable

1156B TRS-80 with buffered
cable

1156C For Apple
^ 1156D For Exidy Sorcerer

HOW TO ORDER:

Pay by check, Mastercharge,
Visa, or COD. Charge orders
please include expiration date,
foreign pay in U.S. funds. Order
by phone or mail, or at our retail.
MINIMUM ORDER $10. please
include phone number and mag-
azine/issue you are ordering
from. Prices valid thru last day of
cover date. SHIPPING: USA::
add $2.00 for the first 2 lbs. For
ground add 354 for addt'l lb. For
air add 75< for addt'l lb. FOR-
EIGN: surface: add $3.00 for first
2 lbs, 604 per addt'l lb. Air: add
$11.00 for first 2 lbs, $5 for each
addt'l lb. CODs $1 addt'l. Guar-
anteed satisfaction for 120 days
or your money back! Not re-
sponsible for typographical
errors. Some items subject to
prior sale. We reserve the right
to limit quantities.

SEND FOR FREE CATALOG
FEATURING:

Computers and accessories, disk
drives, printers, integrated cir-
cuits, LEDs, semiconductors,
books, software, connectors,
plus more and more! The widest
selection at the lowest prices!
Circle our reader service number
phone/write today for your

Lcopy!

r ATARI

THE AFFORDABLE COMPUTER

The perfect computer for
Sophisticated, yet simple. De-
signed by the expert in home
computer based accessories. It
won't become obsolete, because
it has an expandable memory,
advanced peripheral compo-
nents, and comprehensive array
of software modules. Whether
you've had programming experi-
ence or not, you'll find yourself
operating your Atari in no time
at all! Features of the Model 400
include: 57 key keyboard, high-
resolution color graphics, built-
in TV modulator for direct con-
nection with any standard color
LTV, 8K RAM, 8K BASIC ROM.

both home and business!

plus more and more! The model
800 has all the features of the j
400 plus two channel digital re-
corder, 8K RAM, (expandable to
48K) and 16K ROM, (expandable
to 32K).

Cat No. Description Price
2172 Atari 400 Per- $550.00
sonal Computer
Digital Recorder 90.00

Atari 800 Per- 995.00
sonal Computer
Minidisk Drive 750.00
for 800

Line Printer for 600.00 J
800

2176

2173

2174

2175

'MICROPROCESSORS!

I Order by Cat No. 999 and type |

TYPE NO. PRICE
Z80 A

RAMS/EPROMS

Order by Cat No. 999 and type

TYPE NO.

PRICE

TYPE NO.

PRICE

1101

.79

TMS 4045-300

7.25

2101-250

1.95

4116-300

11.65

2101-450

1.25

4116-250

12.75

21 L02-650

.79

4116-200

13.75

21 L02-450

1.10

4116-150

14.90

21 L02-250

1.25

9050 CDC

4.50

2111-400

2.95

91 L02-450

.79

2114-300

7.25

1702 A

4.25

2114-200

9.75

TMS 2532

86.00

4027P-2

3.90

2708

9.15

TMS 4045-450

6.50

•• 2716

36.75

CMOS

TYPE

NO.

PRICE

TYPE

NO.

PRICE

CD 4000

.19

CD 4028

.85

CD 4001

.23

CD 4030

.45

CD 4002

.23

CD 4035

.99

CD 4006

1.09

CD 4040

1.10

CD 4007

.25

CD 4044

.79

CD 4008

.28

CD 4045

.89

CD 4009

.45

CD 4046

1.19

CD 4010

.39

CD 4049

.45

CD 4011

.28

CD 4050

.45

CD 4012

.25

CD 4051

1.15

CD 4013

.36

CD 4052

.69

CD 4014

.99

CD 4053

1.19

CD 4015

.99

CD 4066

.85

CD 4016

.45

CD 4069

.49

CD 4017

1.10

CD 4071

.26

1 CD 4018

:99

CD 4081

.29

1 CD 4019

.42

CD 4082

.29

CD 4020

1.10

CD 4510

.99

CD 4021

1.25

CD 4516

.79

CD 4022

1.10

CD 4519

.59

CD 4023

.29

CD 4522

1.25

CD 4024

.75

CD 4526

1.25

CD 4025

.26

CD 4528

.99

CD 4026

1.45

CD 4529

.49

^CD 4027

.49

74LS

I Order by Cat No. 999 and type I

74C

TYPE ,
NO. 1
I 74C 08
I 74C 10
I 74C 74
I 74C 76
I 74C174
I 74092

74*

74H

TYPE ,
NO. 1
I 74H 04
I 74H 10
I 74H 20
I 74H 30
I 74H 53
I 74H 54
I 74H103

74L

-

I 74L 30
I 74L 42
I 74L 73
I 74L 74
I 741 75
1 74L192 1

I Order by Cat No. 999 and type J

TYPE ,
NO.
74$ 00
74$ 04
74$ 10
74$ 20
74$ 30
74$ 38
74$ 40
74$ 64
74$ 86
74$157
74$ 158
74$187
74$188
74$196
74$197
74$240
745241
74$251
74$260
74$274
74$373
74$387
74$412
74$470

TYPE

NO.

PRICE

TYPE

NO.

74 L$ 00

.28

74LS157

74 L$ 01

.19

74LS158

74L$ 02

.29

74 LSI 60

74L$ 03

.19

74LS161

74 L$ 04

.89

74 LSI 62

74L$ 05

.35

74LS163

74 L$ 08

.29

74 LSI 64

74LS 09

.25

74LS165

74L$ 10

.29

74LS168

74L$ 11

.59

74LS169

74L$ 12

.29

74 L$1 70

74L$ 13

.59

74LS173

74L$ 14

1.25

74LS174

74L$ 15

.39

74LS175

74L$ 20

.29

74LS181

74L$ 21

.29

74LS190

74L$ 22

.29

74LS191

74 L$ 26

.25

74LS192

74L$ 27

.35

74 LSI 93

74L$ 28

.39

74 LSI 94

74L$ 30

.29

74LS195

74L$ 32

.39

74 LSI 96

74L$ 33

.39

74LS197

74L$ 37

.39

74LS221

74L$ 38

.32

74LS240

74L$ 40

.33

74LS241

74L$ 42

.89

74LS242

74L$ 47

.89

74LS243

74LS 48

.79

74LS244

74L$ 51

.29

74LS247

74 L$ 54

.29

74LS248

74 L$ 55

.29

74LS251

74 L$ 73

.44

74LS253

74 L$ 74

.59

74LS257

74L$ 75

.49

74LS258

74 L$ 76

.45

74LS259

74L$ 83

.89

74LS260

74L$ 85

1.25

74LS261

74LS 86

.45

74LS266

74L$ 90

.49

74LS273

74 L$ 92

.75

74LS275

74L$ 93

.59

74LS279

74L$ 95

.99

74LS283

74L$ 96

1.15

74LS293

74 LSI 07

.39

74LS295

74 L$1 09

.45

74LS298

74 LSI 12

.29

74LS365

74LS113

.29

74LS366

74LS114

.29

74LS367

74LS122

.49

74LS368

74LS123

.99

74LS373

74LS124

1.35

74LS374

74LS125

.89

74LS377

74LS126

.39

74LS378

74LS132

.79

74LS386

74LS138

.88

74LS393

74LS139

.88

74LS395

74LS145

1.25

74LS399

74LS151

.67

74LS424

74LS153

.79

74 L $668

74LS154

1.79

74LS670

74LS155

.89

81 LS 96

i 7 4 L$1 50

.69

01L$ 97

Type

11C90

AY5-1013A

AY5-1014A

FD1771B01

BR1941L

KR2376-ST

2513

7107

ICM7207 A/7208

8038

DM8131

DM8833

DM8836

TA7205P

SN76477

MM5375AC

IH5004

MC14410

MC14411

8271

Special Purpose IC’s

Order by Cat No. 999 and type

Description
650 MHz prescaler
UART, 30K baud
U ART, 40K baud
Floppy disk controller
Dual baud rate gen
ASCII keyboard encoder
Character gen, upper case
DPM, led
Frequency counter
Voltage controlled oscillator
6-bit bus comparator
single ended line trans
line receiver, single ended
4.8 watt audio amp
Sound generator
6 digit clock, com anode
2xSPST jfet switch w/driver
Touch tone encoder
Baud rate generator, 1MHz
Floppy disk controller

PRICE

16.50

4.50
7.75

39.00

9.50
9.50
9.50

10.75

24.00
3.95
2.40

.90

8.50

15.00

17.50

TTL

J Order by Cat No. 999 and type

| TYPE NO. PRICE TYPE NO. PRICE
7400 .16 74109 .55

7401

7402

7403

7404

7405

7406

7407

7408

7409

7410

7411

7412

7413

7414

7416

7417
7420

7422

7423

7425

7426
7430
7432

7437

7438

.18

.18

74116 1.95

74120 1.25

74121 .35

74122 .39

74123 .49

74125 .39

74126 .44

74128 .49

74132 .69

74136 .75

74139 .69

74141 .79

74143 2.75

74145 .65

74148 1.25

74150 .89

74151 .59

74153 59

74154 .99.

74155 .75

74156 1.12

74157 .65

74160 .85

.74161 .79

74162

LINEARS

Order by Cat No. 999 and type

TYPE

NO.

PRICE

TYPE

NO.

PRICE

101 H

1.79

340 K-24

1.75

103 H-3.9

1.39

340 T-5

.99

103 H-5.1

1.39

340 T-6

.99

103 H-5.6

1.39

340 T-8

.99

301 AH

.39

340 T-12

.99

301 AN-8

.32

340 T-15

.99

304 H

2.25

340 T-18

99

305 H

1.30

340 T-24

.99

307 N

.49

358 N-8

.59

308 H

.79

379 M

5.75

308 N-8

.59

381 N

2.75

308 AH

.99

386 N

.79

309 H

1.10

387 AN

1.25

309 K

1.50

389 N

1.85

311 H

.88

394 H

3.50

311 N

.88

555 N-8

.35

311 N-8

.49

556 N

.79

312 H

1.95

565 N

99

317 T

2.75

567 N

99

317 H

2.75

703 N-8

49

318 N-8

.79

709 N-8

.25

319 H

1.30

723 N

49

320 H-5

.95

741 N

.39 J

320 H-6

.95

741 N-8

.39

320 H-12

.95

741 H

.79

320 H-15

.95

747 H

1.25

320 H-24

.95

747 N

1.25

320 K-5

1.90

1455

1.25

320 K-12

1.90

1458 N-8

.49

320 K-15

1.85

1488 N

1.49

320 K-24

1.85

1489 N

1.39

320 T-5

1.10

1889 N

2.95

320 T-12

1.10

2900 N

.99

320 T-15

1.10

3302

.39

320 T-24

1.10

3401

.55

321 H

6.50

3900

.55

322 H

1.75

3911

.99

323 K

5.95

4194

5.95

324 N

.89

4250

1.25

339 N

.99

5369 N-8

1.95

340 K-5

1.75

75451

.39

340 K-8

1.75

75452

.79

340 K-12

1.75

75453

.49

340 K-15

1.75

75491

.99

^40 K- 18

1.75

TYPE NO. PRICE

7439 .27

7440 .45

7441 .70

7442 .49

7443 .59

7444 .59

7445 69

7446 69

7447 59

7448 .69

7450 19

7451 19

7453 19

7454 .19

7460 19

7470 33

7472 28

7473 35

7474 -29

7475 .39

7476 .35

7479 4.75

7480 49

7481 .99

7482 99

7483 .59

7485 69

7486 35

7489 1.75

7490 39

7491 .55

7492 43

7493 43

7494 .79

7495 .65

7496 .65

7497 2.90

74100 1.42

74107 .29

TYPE NO.

74163

74164

74165

74166
74170

74173

74174

74175

74176

74177
74179
74780

74181

74182

74184

74185

74190

74191

74192

74193

74194

74195

74196

74197

74198

74199
74221
74251
74273

74278

74279
74298

74365

74366
74376
74368
74393
8T97

PRICE

.79

VOLTAGE
REGULATORS ,

Order by Cat No. 999 and type I

Type
LM320K5
LM320K12
LM320K15
LM340K5
LM340K12
LM340K15
LM340K18
7805T
7806T
781 2T
781 5T
7818T
7824T
7905 T
791 2T
791 5T

r CENTRONCS 730-1

MINIPRINTER

Provides greater flexibility than
any other printer we've offered.
Prints on either roll, sheet, or
fanfold; allows you to print on
your letterhead, payroll checks,
etc, taking the place of many
printers. Simple design and con-
struction ensure reliability. Sold
nationally by a large electronics
chain for $100 over our price!
7x7 dot matrix for crisp, clean
characters. Wt 12 lbs. |
kCat No. 2213

$995j

19511 Business Center Dr Dept. K1 Northridge, Ca. 91324

v* Reader Service— see page 227

v* H25

Microcomputing January 1980 195

Save $ on TRS-80 Products

TREMENDOUS
SAVINGS ON
^ TRS-80 SYSTEMS

Complete system includes:

TRS-80 Level II, w/our48K RAM, Dual MPI
Disk Drives, and the APPARAT DOS+ soft-
ware ($2500 value), only $2049. Line printer
and desk options available.

SUPERDISK

TF-7D Micropolis Largest capacity
mini floppy, up to 1 95 Kbytes
on 77 tracks with 77TK DOS+ $699

Send for FREE
Catalog

A Complete Family
Of Disk Drives
To Choose
From . . .

In Stock

TF-1 Pertec FD200, 5V4”, 40 track use both sides $379

TF-3 Shugart SA400, 5V4”, 35 tracks same as tandy $389

TF-5 MPI 5V4" 40 track door lock and auto diskette $379

ejection

TDH-1 Pertec Dual Head mini-floppy 35 track same $499

capacity as 2 drives

All disk drive systems come complete with power supply and
chassis

• Two drive cable= $25 • Four drive cable= $35

PRINTERS PRINTERS PRINTERS PRINTERS

LP779 Centronics 779
w/tractors

LP700 Centronics 700
LP701 Centronics 701
NEC Spinwriter

$1099

$1175

$1759

$2499

CENTRONICS 703

LP702 Centronics 702 $1899

LP703 Centronics $2540

LP1 Centronics PI $ 399

Centronics cables $ 39

Add-on Disk Drives

DOES NOT INCLUDE POWER SUPPLY OR CHASSIS

• Pertec FD200 or MPI B-52

• Shugart SA400 (unused)

• Pertec Dual Head

$272.00

$282.00

$399.00

NEW PRODUCTS

• Small System RS232 Interface $ 49.00

• Expansion Interface w/32K $499.00

• AC Line Interference Eliminator $ 18.95

• AC Isolator (6 connectors) $ 45.95

• Telephone Interface $179.95

• Verbatum 5” soft sector Diskettes $ 3.39

IMPROVE TRS-80
PERFORMANCE WITH
NEWDOS+

Over 200 modifications,
corrections and enhance-
ments to TRS DOS.

Includes utilities. Available in
two versions:

35 Track version $99
40 T rack version $110

All prices cash discounted.
Freight FOB/Factory

Memory

16KM 16K RAM Kit
Computer $74
Expansion Interface $78

Software

• Accounts Receivable $39

• Inventory Control $39

• Job Entry/Status $75

• General Ledger $79

• Game Diskette $19

• AJA Word Processor $75

/VIICROCO/MPUrER

TECHNOLOGY

INCORPORATED

2080 South Grand Ave.
Santa Ana, CA 92705
(714) 979-9923

6000 E. Evans Ave., Bldg. 2
Denver, CO 80222
(303) 758-7275

pparat, Inc

is M82

196 Microcomputing January 1980

Radio Shack -Your No. 1 Parts. Place®

Low Prices and New Items Every Dav!

Low-Power
Schottky ICs

ttky ICs

u,„ 490 ng&r

• 100% Prime

• Guaranteed Specs

Improved 5-volt logic devices use
Schottky diode technology for
minimum propagation delay and
high speed at minimum power.

Type

Cat. No.

ONLY

74LS00

276-1900

.49

74LS02

276-1902

.59

74LS04

276-1904

.59

74LS08

276-1908

.49

74LS10

276-1910

.59

74LS13

276-1911

.99

74LS20

276-1912

.59

74LS27

276-1913

.69

74LS30

276-1914

.59

74LS32

276-1915

.69

74LS47

276-1916

1.29

74LS51

276-1917

.59

74LS73

276-1918

.69

74LS74

276-1919

.69

74LS75

276-1920

.99

74LS76

276-1921

.79

74LS85

276-1922

1.29

74LS90

276-1923

.99

74LS92

276-1924

.99

74LS93

276-1925

.99

74LS123

276-1926

1.19

74LS132

276-1927

.99

74LS151

276-1929

.99

74LS157

276-1930

1.19

74LS161

276-1931

1.49

74LS164

276-1932

1.49

74LS175

276-1934

1.19

74LS192

276-1935

1.49

74LS193

276-1936

1.49

74LS194

276-1937

1.49

74LS196

276-1938

1.59

74LS367

276-1835

1.19

74LS368

276-1836

1.19

74LS373

276-1943

2.39

74LS374

276-1944

2.39

4000-Series CMOS ICs

Type

Cat. No.

EACH

4001

276-2401

.69

4011

276-2411

.69

4012

276-2412

.79

4013

276-2413

.99

4017

276-2417

1.69

4020

276-2420

1.69

4021

276-2421

1.69

4023

276-2423

.69

4027

276-2427

.99

4028

276-2428

1.29

4046

276-2446

1.89

4511

276-2447

1.69

4049

276-2449

.79

4050

276-2450

.79

4051

276-2451

1.49

4066

276-2466

1.39

4070

276-2470

.79

4518

276-2490

1.49

4543

276-2491

1.99

All Prime from Major Semi-
conductor Manufacturers.
Specs and Pin Out Diagram
Included with Each Device.

>99

MC14553 3-Digit
BCD Counter 1C

CMOS chip replaces over 8 separate ICs in
a digital display circuit. Input pulse shaping.
Master reset pin. 16-pin DIP.

276-2498 2.99

RAM Memory ICs 049

Low As

2102 1024 x 1 Array. Low-cost static memory chip.
16-pin DIP. Buy 8 and save!

276-2501 2.49 Ea. or 8/14.95

2114L 1024 x 4 Array. NMOS static RAM. 18-pin
DIP. 276-2504 10.99

NEW! Silicon Solar Cells

f

Low As

:99

Convert light to electrical power. All deliver
0.45V at rated current. Use several in series/
parallel for higher voltages or current.
276-122. VS 3" cell. Rated 500 mA 5.99
276-123. Full 3" cell. Rated 1 amp . . . 8.99

Hall-Effect Sensors

I 98 .??

Open-Collector Output

Detects magnetic fields electronically. 750
gauss “on’ threshold. Constant amplitude
independent of frequency. Similar to type
ULN 3006. Ideal for tachs, position sensing,
pulse counting. 5 to 16V supply. T0-92
case. With data.

276-1646 Pkg. of 3/1.98

Unique LEDs

a

® Tri-Color. Displays red, green, yellow.
Uniform light output of 0.6 mcd. Forward
voltage: 2.2VDC. Max. current: 25mA. TI-^4
case style.

276-035 1.39

® Red Flasher. Operates directly from
5VDC power source. Pulse rate: 3 Hz. Max.
current: 20 mA at 5VDC.

276-036 1.29

NEW! Switches

Low As

m !■ *|69 ®

® Submini Push Switches. One red,
one black. SPST momentary contacts
rated 0.5A, 125VAC. Normally open.

275-1571 Pkg. 2/1.69

1] Compact Lever Switches. 6A at

125VAC. SPST. 275-257 2.49

DPDT. 275-259 2.99

BIFET Op Amps

”

Low

As

©

“| 89

Feature very high input impedance, low
noise. Fast 13Vp.S slew rate is ideal for low
TIM distortion audio amplifiers. Internally
compensated. Up to ± 18V supply,
a LF 353N. Dual BIFET Op amp. 8-pin DIP.

276-1715 1.89

11 TL 084C. Quad BIFET Op amp. 14-pin
DIP. 276-1714 2.99

LED Bar/Dot Display
Driver

>49

LM3914N. Features 10 adjustable analog
steps, bar or dot display mode. Current-
regulated LED ouputs. 8 to 25VDC supply.

18-pin DIP. 276-1707 3.49

LM3915N. As above but with 3 dB log steps.
276-1708 3.49

Manufacturer’s Data Books

Low As

295

Need Info?— Find it
at Radio Shack!

[Aj Motorola RF Data Manual. Power and small-signal RF transis-
tors, hybrid amplifier modules, more. 62-1380 4.95

[1 Motorola Low-Power Schottky TTL. Data and diagrams plus

selection guide for choosing best device. 62-1381 3.95

m Linear Applications, Vol. 2. Latest data, diagrams, applica-
tions briefs and articles. Indexed. 62-1374 2.95

d CMOS Integrated Circuits. Covers 74C, CD4000-series with
complete data, diagrams. Cross referenced. 62-1375 3.95

\E Memory Data Book. Complete info on MOS and bipolar mem-
ory components, support circuits. 62-1376 3.95

NEW! BNC Connectors

_ &

I®

*|49 2 19

[a] Type 1094 Female BNC. Mounts in sin

gle^is" hole. 278-105 1.49

1] Type UG-88 Male BNC. No soldering!
Screws onto standard coax cable. Plated
finish.

For RG-58/U Cable. 278-103 2.19

For RG-59/U Cable. 278-104 2.19

SN-76477 “Music
Synthesizer” 1C

Creates almost any type of sound! High
level op amp output. Includes 2 VCOs,
low frequency osc., noise generator, fil-
ter, 2 mixers, timing logic. 28-pin DIP.
With data. 276-1765 2.99

AC and DC
Relays

® SPST Solid State AC Relay. Handles 24
to 280VAC at up to 1.5A. TTL compatible
5VDC control input. 1500VRMS isolation.

275-236 1.99

1] 12VDC SPOT. Silver-plated contacts: 1A
at 125 VAC. 275-231 2.49

4" Cooling Fan

1 2 95

Super

Quiet

Operation

Ideal for cooling power supplies, microcomputers, hi-fi
and Ham gear. Delivers up to 70 CFM. Diecast ven-
turi. U.L. recognized motor. For 120VAC, 60 Hz.

273-241 12.95

12/24-Hr. LCD
Clock Module

19

95

24-Hour Alarm
Shows Time/Day/Date

Actual Size

Complete clock module — just add switches and battery! 0.25"
LCD display has built-in backlight, alarm set, PM and snooze
indicators. Operates up to a year on single 1 .5V battery. Accu-
racy: ± 1 3 seconds per month. 277-1 005 1 9.95

WHY WAIT FOR MAIL ORDER DELIVERY?
IN STOCK NOW AT OUR STORE NEAR YOU!

► Radio /hack

A DIVISION OF TANDY CORPORATION • FORT WORTH, TEXAS 76102
OVER 7000 LOCATIONS IN 40 COUNTRIES

COMPUCRUISE

Put a computer in
your car, which gives
you the most effec-
tive and functional
cruise control ever
designed, plus com-
plete trip computing,
fuel management sys-
tems, and a remark-
able accurate quartz
crystal time system.
So simple a child can
operate, the new
CompuCruise com-
bines latest computer
technology with
state-of-the-art re-
liability in a package
which will not likely be
available on new cars
for years to come •
Cruise Control •Time,
E.T., Lap Timer, Alarm

• Time, Distance. Fuel
to Arrival • Time, Dis-
tance, Fuel to Empty •
Time, Distance and
Fuel on Trip • Current
or Average MPG,
GPH • Fuel Used, Dis-
tance since Fillup •
Current and Aver-
age-Vehicle Speed •
Inside. Outside or
Coolant Temperature

• Battery Voltage •
English or Metric
Display. $199.95 ,
without cruise con-
trol $159.95.

FLOPPY DISK
STORAGE BINDER

This black vinyl
three-ring binder
comes with ten
transparent plastic
sleeves which ac-
commodate either
twenty, five-inch or
ten, eight-inch floppy
disks. The plastic
sleeves may be or-
dered separately and
added as needed. A
contents file is in-
cluded with each
sleeve for easy iden-
tification and organiz-
ing. Binder & 10 hol-
ders $14.95 Part No.
B800; Extra holders
95* each. Part No.
800

OPTO-ISOLATED
PARALLEL INPUT
BOARD FOR
APPLE II

There are 8 in-
puts that can be dri-
ven from TTL logic or
any 5 volt source.The
circuit board can be
plugged into any of
the 8 sockets of your
Apple II. It has a 16 pin
socket for standard
dip ribbon cable con-
nection.

Board only $15.00.
Part No. 120, with
parts $69.95. Part
No. 120A.

TIDMA

• Tape Interface Direct
Memory Access • Re-
cord and play programs
without bootstrap load-
er (no prom) has FSK
encoder/decoder for
direct connections to
low cost recorder at
1 200 baud rate, and
direct connections for
inputs and outputs to
a digital recorder at
any baud rate • S-1 00
bus compatible • Board
only $35.00 Part No.
112, with parts $110
Part No. 1 1 2A

SYSTEM

MONITOR

8080, 8085. or Z-80
System monitor for use
with the TIDMA board.
There is no need for the
front panel. Complete
with documentation
$12.95.

16K EPROM

Uses 2708 EPROMS,
memory speed selec-
tion provided, ad-
dressable anywhere in
65K of memory, can
be shadowed in 4K in-
crements. Board only
$24.95 part no.
7902, with parts less
EPROMs $49.95 part
no. 7902A.

ASCII KEYBOARD

TTL & DTL compatible • Full 67 key array

• Full 128 character ASCII output • Positive
logic with outputs resting low • Data Strobe

• Five user-definable spare keys • Standard
22 pin dual card edge connector • Requires
+5VDC, 325 mA. Assembled & Tested.
Cherry Pro Part No. P70-05AB. $119.95.

ASCII KEYBOARD

53 Keys popular ASR-33 format • Rugged
G-10 P. C. Board • Tri-mode MOS encoding
• Two-Key Rollover • MOS/DTL/TTL Compat-
ible • Upper Case lockout • Data and Strobe
inversion option • Three User Definable
Keys • Low contact bounce • Selectable Par-
ity • Custom Keycaps • George Risk Model
753. Requires +5, -12 volts. $59.95 Kit.

ASCII TO CORRESPONDENCE
CODE CONVERTER

This bidirectional board is a direct replace-
ment for the board inside the Trendata 1000
terminal. The on board connector provides
RS-232 serial in and out. Sold only as an
assembled and tested unit for $229.95.
Part No. TA1000C

DISK JACKET™

Made from heavy duty
.0095 matte plastic
with reinforced

grommets. The mini-
diskette version holds
two 5-1/4 inch disk-
ettes and will fit any
standard three ring
binder. The pockets to
the left of the disk-
ette can be used for
listing the contents of
the disk. Please order
only in multitudes of
ten. $9.95/10 Pack.

ATARI 800

Computer with 8K
$995.00, disk drive
$549.00, printer
$599.99

s

VIDEO TERMINAL

16 lines, 64 columns •
Upper and lower case

• 5x7 dot matrix • Se-
rial RS-232 in and out
with TTL parallel
keyboard input • On
board baud rate
generator 75, 1 10,
150, 300, 600, &
1200 jumper select-
able • Memory 1024
characters (7-21 L02)

• Video processor chip
SFF96364 by Necu-
lonic • Control char-
acters CCR, LF, -+,

t, i, non destructive
cursor, CS, home, CL

• White characters on
black background or
vice-versa • With the
addition of a key-
board, video monitor
or TV set with TV
interface (part no.
107A) and power
supply this is a com-
plete stand alone
terminal • also S-1 00
compatible • requires
+ 16, & -16 VDC at
100mA, and 8VDC at
1 A. Part No. 1000A
$199.95 kit.

RS-232/20mA

INTERFACE

This board has two
passive, opto-isola-
ted circuits. One con-
verts RS-232 to
20mA, the other con-
verts 20mA to RS-
232. All connections
go to a 10 pin edge
connector. Requires
+12 and -12 volts.
Board only $9.95,
part no. 7901, with
parts $14.95 Part
No. 7901A.

COMPUCOLOR II

Model 3, 8K $13 95,
Model 4, 16K $15 95,
Model 5, 32K $18 95.
Prices include color
monitor, computer,
and one disk drive.

PET COMPUTER

With 32K & monitor -
$1195. Dual Disk
Drive - $1195.

APPLE II PLUS

16K

$979.00

\

CASSETTE TAPE
ERASER

REMOVES RECORD-
INGS IN GNE SEC-
OND! The process
eliminates static pos-
itive / negative ions
and maintains original
tone quality with min-
imal tape hiss • To im-
prove tone quality • To
reduce hissing • For
quick and easy to
erase • No battery or
liquid required • Pow-
erful and effective ac-
tion • Unconditional 2
year guarantee.
ERASER-8 $19.95.

16K RAMS

For the Apple,
TRS-80 or Pet $8
each Part No. 41 1 6/
2117.

APPLE II HOBBY/
PROTOTYPING
CARD

$14.95 Part No.
7907

T.V. INTERFACE

• Converts video to
AM modulated RF,
Channels 2 or 3. So
powerful almost no
tuning is required. On
board regulated power
supply makes this ex-
tremely stable. Rated
very highly in Doctor
Dobbs' Journal. Recom-
mended by Apple •
Power required is 12
volts AC C.T., or +5
volts DC • Board only
$7.60 part No. 107,
with parts $1 3.50 Part
No. 1 07A

PARALLEL TRIAC
OUTPUT BOARD
FOR APPLE II

This board has 8 tnacs capable of
switching 110 volt 6 amp loads (660 watts
per channel) or a total of 5280 watts. Board
only $15.00 Part No. 210, with parts
$119.95 Part No. 21 OA.

Tq 0rHgr • Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order.
IV \J l Vw . We accept . c.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no.,
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han-
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line [408) 448-0800

Send for FREE Catalog ... a big self-addressed envelope with 41* postage gets it fastest!

.ELECTRONIC SYSTEMS ° p<

KB P. 0. Box 21638, San Jose, CA USA 95151

198 Microcomputing January 1980

is E21

SERIAL I/O

• Can input into basic

• Can use LUST and
LPRINT to output, or
output continuously •
RS-232 compatible •
Can be used with or
without the expansion
bus • On board switch
selectable baud rates
of 110,150,300,600,
1 200, 2400, parity or
no parity odd or even,
5 to 8 data bits, and 1
or 2 stop bits. D.T.R.
line • Requires +5,
-1 2 VDC • Board only
$19.95 Part No. 8010,
with parts $59.95 Part
No. 801 OA, assembled
$79.95 Part No. 80 10
C. No connectors pro-
vided, see below.

EIA/RS-232 con-
nector Part No.

DB25P $600, with
9'. 8 conductor

cable $10.95 Part
No. DB25P9.

3' ribbon cable
with attached con-

. nectors to fit TRS-

BO end our serial
board $19 95 Part
No. 3CAB40

RS-232/ TTL
INTERFACE

• Converts TTL to RS-
232, and converts RS-
232 to TTL • Two sep-
arate circuits • Re-
quires -12 and +12
volts • All connections
go to a 10 pin gold
plated edge connector,
kit $ 9.95 Part No.
232A 10 Pin edge
connector $3.00 Part
No. 1 0P.

• Type 103# Full or
half duplex • Works up
to 300 baud • Origi-
nate or Answer • No
coils, only low cost
components • TTL in-
put and output-serial

• Connect 8 H speak-
er and crystal mic.
directly to board •
Uses XR FSK demod-
ulator • Requires +5
volts • Board only
$7.60 Part No. 109,
with parts $27.50 Part
No. 1 09A

DISKETTES

Box of 10, 5" $29.95,
8" $39.95.

Plastic box, holds 10
diskettes, 5" - $4.50,
8” -$6.50.

RS-232/TTY

INTERFACE

This board has two
active circuits, one
converts RS-232 to
20mA, and the other
converts 20mA to
RS-232. Requires
+12 and -12 volts.
$9.9 5 Part No. 600A
Kit.

part wo too

S-100 BUS
ACTIVE TERMINATOR

Board only $14.95 Part No. 900, with parts
$24.95 Part No. 900A

: -rmi.m'

apple II-::-

SERIAL I/O
INTERFACE

Baud rate is continuously adjustable from 0
to 30,000 • Plugs into any peripheral
connector • Low current drain. RS-232 input
and output • On board switch selectable 5 to
8 data bits, 1 or 2 stop bits, and parity or no
parity either odd or even • Jumper selectable
address • SOFTWARE • Input and Output
routine from monitor or BASIC to teletype or
other serial printer • Program for using an
Apple II for a video or an intelligent terminal.
Also can output in correspondence code to
interface with some selectrics. • Also
watches DTR • Board only $1 5.00 Part No.
2. with parts $42.00 Part No. 2A, assembled
$62.00 Part No. 2C

8K EPROM piiceon

Saves programs on PROM permanently (until
erased via UV light) up to 8K bytes. Programs
may be directly run from the program saver
such as fixed routines or assemblers. • S-
100 bus compatible • Room for 8K bytes of
EPROM non-volatile memory (2708‘s). • On-
board PROM programming • Address
relocation of each 4K of memory to any 4K
boundary within 64K • Power on jump and
reset jump option for '‘turnkey" systems and
computers without a front panel • Program
saver software available • Solder mask both
sides • Full silkscreen for easy assembly.
Program saver software in 1 2708 EPROM
$25, Bare board $35 including custom coil,
board with parts but no EPROMS $139, with
4 EPROMS $179, with 8 EPROMS $219.

WAMECO PRODUCTS
WITH

ELECTRONIC SYSTEMS PARTS

FDC-1 FLOPPY CONTROLLER BOARD will
drive shugart, pertek, remex 5" & 8" drives
up to 8 drives, on board PROM with power
boot up, will operate with CPM (not

included). PCBD $42.95

FPB-1 Front Panel. (Finally) IMSAI size hex
displays. Byte or instruction single step.

PCBD $42.95

MEM-1 A 8Kx8 fully buffered. S-100, uses
2102 type RAMS

PCBD $24.95, $168 Kit

QMB-12 MOTHER BOARD, 1 3 slot, termi-
nated, S-100 board only $34.95

$89 95 Kit

CPU-1 8080A Processor board S-100 with
8 level vector interrupt PCBD . . $25.95
$89.95 Kit

RTC-1 Realtime clock board. Two independ-
ent interrupts. Software programmable.

PCBD $25.95, $60.95 Kit

EPM-1 1702A 4K EPROM

card PCBD $25.95

$49.95 with parts less EPROMS
EPM-2 2708/2716 16K/32K

EPROM card PCBD $24.95

$49.95 with parts less EPROMS
QMB-9 MOTHER BOARD. Short Version of

QMB-12. 9 Slots PCBD $30.95

$67.95 Kit

MEM-2 1 6Kx8 Fully Buffered 2114 Board
PCBD $25.95, $269.95 Kit

T.V.

TYPEWRITER

• Stand alone TVT

• 32 char/line, 16
lines, modifications for
64 char/line included

• Parallel ASCII (TTL)
input • Video output

• 1 K on board memory

• Output for computer
controlled curser •
Auto scroll • Non-
destructive curser •
Curser inputs: up, down,
left, right, home, EOL
EOS • Scroll up, down

• Requires +5 volts
at 1.5 amps, and -12
volts at 30 mA • All
7400, TTL chips •
Char. gen. 2513 •
Upper case only •
Board only $39.00
Part No. 106, with
parts $145.00 Part
No. 1 06A

UART &
BAUD RATE
GENERATOR

• Converts serial to
parallel and parallel to
serial • Low cost on
board baud rate gener-
ator • Baud rates:
110, 150, 300, 600,
1200, and 2400 •
Low power drain +5
volts and -12 volts
required • TTL com-
patible • All characters
contain a start bit. 5
to 8 data bits, 1 or 2
stop bits, and either
odd or even parity. • All
connections go to a 44
pin gold plated edge
connector • Board only
$12.00 Part No. 101,
with parts $35.00 Part
No. 101 A, 44 pin edge
connector $4.00 Part
No. 44P

TAPE
INTERFACE

• Play and record Kan-
sas City Standard tapes

• Converts a low cost
tape recorder to a
digital recorder • Works
up to 1200 baud •Dig-
ital in and out are TTL-
serial • Output of
board connects to mic.
in of recorder • Ear-
phone of recorder con-
nects to input on board

• No coils • Requires
+5 volts, low power
drain • Board only
$7.60 Part No. Ill,
with parts $27.50 Part
No. 1 1 1 A

HEX ENCODED

KEYBOARD

E.S.

This HEX keyboard
has 1 9 keys. 1 6 encod-
ed with 3 user defin-
able. The encoded TTL
outputs. 8-4-2-1 and
STROBE are debounced
and available in true
and complement form.
Four onboard LEDs
indicate the HEX code
generated for each
key depression. The
board requires a single
+5 volt supply. Board
only $15.00 Part No.
HEX-3, with parts
$49.95 Part No. HEX-
3A. 44 pin edge con-
nector $4.00 Part No.
44P.

£1

DC POWER SUPPLY

• Board supplies a regulated +5
volts at 3 amps., +1 2, -1 2, and -5
volts at 1 amp. • Power required is
8 volts AC at 3 amps., and 24 volts
AC C.T. at 1.5 amps. • Board only
$12.50 Part No. 6085, with parts
excluding transformers $42.50
Part No. 6085A

Tq QrHpr . Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order.

iuo . We accept c.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no.,
B [AA| shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han-
wmi wBi dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408] 448-0800

Send for FREE Catalog ... a big self-addressed envelope with 41 * postage gets it fastest!

.ELECTRONIC SYSTEMS

KB , P. 0. Box 21638, San Jose, CA USA 95151

v* Reader Service— see page 227

Microcomputing January 1980 199

LOOK FOR OUR HUGE AD IN JANUARY BYTE

SAVE s 100 00
DM2700S DISK &
CABINET with
POWER SUPPLY

DM2700S includes Siemans FD120-8"
Disk Drive with the following features:

•Single or Double Density

•Hard or Soft Sector

•Door Interlock

•Write Protect

•Hard Sector Detection

•500 KB/S Transfer

•800 KB unformated

• Bit density 6536 BP1

•Shugart 800 Series Compatable

Cabinet includes:

•110V to 125V 60 Hz power supply

•Data Cable

•Fan

•Accepts per SCI, Shugart,

Siemans 8" Drives

SHOP AND COMPARE
DM2700S Disk Drive & Cabinet
Reg.$750 Sale Priced $650

The Vista V80:
widen the ability of your
TRS-80 $395.00

The Vista V80 Mini Disk System is the perfect way to widen the capabilities of
your TRS-80* Micro-computer. Quickly and inexpensively. Our $395 price tag is
about $100 less than the Radio Shack equivalent. Our delivery time is immediate.
And our system is fully interchangeable. That’s just the start.

It will give you 23% more storage capacity by increasing useable storage from
55,000 to 65,000 bytes per drive with our new software patch.

It can work 8 times faster than the TRS-80 Mini-Disk system, because track-to-
track access is 5ms versus 40ms for the TRS-80. You can realize this added speed
once the new double disk expansion interface is available without expensive
modification of the existing unit.

It has a better warranty than any comparable unit warranty available • a full 120
days on all parts and service. When you consider how much more goes into the
Vista V80, that shows a lot of faith in our product.

A full 3 amp power supply means you have 2 V* times the power necessary to
operate the V80, and full ventilation insures that there will be no problems due to
overheating.

The Vista V80 Mini Disk System requires Level II Basic with 16 K RAM Expansion
interface (it operates from the Radio Shack interface system. It comes complete
with a dependable MPI Minifloppy disk drive, power supply, regulator board and
vented case. It's shipped to you ready to run-simply take it out of the box and plug it
in. You’re in business. From the company that means business - Vista Computer
Company.

DATA CABLES, VC80-2 (2 drive) 8 29.95

DATA CABLES, VC80-4 (4 drive) 5 39:95

SPECIAL: Box of 10 diskettes • $20.00 with Purchase of VISTA 80

FDD120-8 $449.00
DM2700 Cabinet, less Drive
Reg. $249 Sale Priced $225.00

' VERSAFLOPPY II 'l

DOUBLE DENSITY, DOUBLE SIDED, DISC.CONTROLLER

GENERAL DESCRIPTION:

Versalloppy II is a flexible disk drive
controller trial incorporates a wide
range of capabilities into one board, it
operates with double density soft sec-
tored format which provides 985.600
bytes of storage on a double sided 8
inch diskette and 129.920 bytes per
side on a five Inch mini diskette, the
Versalloppy II directly controls many
popular disk drives. These include:
Shugarl SA400 and SA450: Shugart
SA800 and SA850; Mayllower MFE500
and MFE700; Per Sci 70 and 277: and
Siemans. BSI-105.

S-100 Bus IEEE Standard
Compatible

IBM-3740 Compatible Soft
Sectored Format tor Single
Density Drives

Operates with both Standard (8")
and Mini (5 ') Drives
Simultaneously
Provides Control (or Double
Sided Operation

Operales with Z80. 8060. and 8085
Central Processing Unit
Controls up lo four drives
Vectored Interrupt Operation
Optional

Control and Diagnostic Software

Available In PROM

SDOS Disk Operating System

M-XVI

The true 16K Static Ram module
for S-100 bus systems.

ASSEMBLED * TESTED ~ 100% BURN IN
The M XVI gives you unbelievable expansion
capability tor your S-100 bus system -even beyond
64K Manufactured to the highest industry stan California Computer Systems
dards documented and designed to make
assembly, use. and programming a snap The
M XVi board is a true revelation Tor the serious
hobbyist and use in practical business or In-

dustrlal applications. .^0 ^ j

FEATURES: gf\i\ M

•Fully static A Th.

•Uses popular 2114 static RAMS

• ♦ 5 volt operation only

•Bank Select available by bank port 1

and bank byte

• Phantom line capability C mMB leC s ±^ 40 tr,.

•Addressable in 4K blocks ^

SHOP & COMPARE SPECIAL

s 290 00

SDSVERSAFLOPPY II KIT
SDSVERSAFLOPPY II A&T

s 390°°

•Addressable in 4K blocks
•4K blocks can be addressed any
where within 64K in 4k increments
•Meets IEEE proposed S-100 signal
standards

•LED indicators lor board selection
end bank selection
• FR 4 epoxy PC boards
•Solder masked on both sides (J
•Silk screen ol part number y
and pari designator JL

'2016BA 450ns 2MHZ I
2016BB 300ns 4MHZ I
2016BY Bare Board only

DISC CONTROLLER
SD “VERSAFLOPPY” KIT

The Versatile Floppy Disk
ContmHer

ONLY *145 00

DISC

DRIVES

THE MICROBYTE M32KSS
32K STATIC MEMORY BOARD
ASSEMBLED & TESTED

SALE PRICED
M32 KSS-L (2 MHz)
List $650

SALE $530.00

M32 KSS-H (4 MHz)

List $680

SALE $560.00

MARRY CHRISTMAS FROM C

PRIORITY ONE ELECTRONICS *

OUR BEST SELLING BOOK

S 4 Reg. $9.50

^ I With a purchase of $50.00 or more

OUR BEST SELLING BOOK]

Limit 1 Book per customer

’Portable Miniscopes for Electronic Professionals

on the Go!!! The Standout Oscilloscope develop-
ment of the decade!!! Now -30MHz, dual trace
model. Compare the performance, then compare
the price.

Reg. *598. 15 MS-230 s 579. 00

1* sale Probes 1 c with purchase of scope

• 30-Megahertz bandwidth • Accuracy 3% full scale. • Internal, line or externanTJ^
ger. • Batteries and charger/transformer unit included • Graticule: 4x5 divisions,
each division 0.25" • Time base: 1 mico sec. to 0.5 sec/div 21 settings • Verticle
Gain: 0.01 to 50 Volts/div. 12 settings. • Size 2.9’’H x 6.4”W x 8.5”D, 3.5 lbs. • TEST
MOST DIGITAL LOGIC CIRCUITS INCLUDING MICROPROCESSORS.*

*41-141 Deluxe lOtol probe with 4 interchangeable tips $27.00

41-37 Deluxe lOtol/ltol probe with 4 Interchangeable tips $38.50

41-180 leather carrying case $45.00

MS-15 Single trace 15 MHz $349.80

LMS-215 Dual trace 15 MHz $465.45

• Fully S100 Bus Compatible, IMSAI, SOL, ALTAIR, ALPHA MICRO. • Uses
National’s Low Power 5257 4K x 1 Static Rams. • 2 MHz or 4MHz operation. • Gold
contacts for higher reliability. • On board single 5 amp regulator. • On board single
5 amp regulator. • Thermally designed heat sink (board operating temperature 0° —
70°C). • Commercially designed power bus, 7 ground bus bars, 0.1 uf decoupling
capacitors. • Fully tri-state buffered. • Inputs fully low power Shottky Schmitt. Trig-
ger buffered on all address and data lines. • Phantom is jumper selectable to pin 67.

• Each 4K hardware or software selectable. • One on board 8-bit output port
enables or disables the 32K in 4K blocks. • Selectable port address. • 4K banks can
be selected or disabled on power on clear or reset. • Will operate with or without
front panel. • Compatible with ALPHA MICRO, with extended memory management
for selection beyond 64K. • No DMA restriction. • Low power consumption 2.3 - 2.5
,amps. • Fully warranted for 120 days from date of shipment.

*«*« I

X MAS SPECIAL
NOVATION CAT
ACOUSTIC MODEM

JUST WRAP TOOL WITH

WHITE

VELLOW

RED

REPLACEMENT ROLL OF

BLUE

WHITE

YELLOW

RED

$ 159 °°

• 0-300 Baud

• Bell 103

• Answer, Originate

JUST WRAP KIT
CONTAINS
•JUST WRAP Tool
•Roll of Blue Wire. 50 ft.
•Roll of White Wire. 50 ft.

• Roll of Yellow Wire, 50 ft.

• Roll of Red Wire. 50 ft.

• Unwrapping Tool

JWK-8, JUST WRAP KIT

$24.95

Why Cut? Why Strip?
Why Silt? WHY NOT...
JUST WRAP

•AUG 30 Wire

• 025 Square Posts

• Daisy Chain or Point
To Point

•No Stripping or Slitting
Required. JUST WRAP

Regular $ 198

PRIORITY ONE ELECTRONICS « „

► 16723K Roscoe Blvd. Sepulveda, CA 91343 fli

Terms: Visa. MC, BAC, Check. Money Order. C.O.D. U.S. Funds Only. CA residents add 6% sales tax.
Minimum order $10.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling, p
MINIMUM $2.50. Excess refunded. Just in case please include your phone no.

Prices subject to change without notice.

“21 We will do our best to maintain prices thru Dec. 1979 OEM and Institut

phone orders welcome (213) 894-8171, (800) 423-5633 inquiries invited.

J213) 894-81 71j

•Built in Cut off
•Easy Loading of Wire
•Available Wire Colors:
Blue. White. Red
& Yellow

MEMORY WAR SHOP AND COMPARE

ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

LOOK FOR OUR HUGE AD IN JANUARY BYTE

LOOK FOR OUR HUGE AD IN JANUARY BYTE

MEMORY WAR SHOP AND COMPARE

4 MHZ EXPANDORAM II KIT

The S-100 Memory Board for the 80’s

SD SYSTEMS’ ExpandoRAM II is a state-of-the-art
dynamic RAM board with capacities from 16K bytes
(4116) to 256 K bytes (4164). It operates on the industry
S-100 Bus. The ExpandoRAM M’s design allows eight
boards to operate from the same S-100 Bus. Page
mode operation provides the system with the capabil-
ity of servicing multiple users without RAM in-
terference. Invisible refresh and synchronization with
wait states provide greater reliability, and processing
speeds up to 4 Mhz.

The ExpandoRAM II is compatible with most S-100
CPU's based on the 280 microprocessor. When other
SD SYSTEMS 200 series boards are combined with the
ExpandoRAM II, they create a microcomputer with ex-
ceptional capabilities and features.

S-100 Bus Compatible
Up to 4Mhz Operation
Expandable Memory from 16K to 256K
DIP Switch Selectable Boundaries
Uses 16K (4115) or 64K (4164) Memory Devices
Page Mode Operation Allows up to 8 Memory
Boards on Bus
Operates with Z80 CPU’s

Phantom Output Disable Sd I©

Invisible Refresh (Synchronized with Price

Wait States)

EXPANDORAM II KIT (4116)

16K $280.00 48K $450.00

32 K $365.00 64K $535.00

4

SD EXPANDORAM The Ultimate S-100 Memory

The EXPANDORAM is available in versions from 16K
up to 64K, so for a minimum investment you can have
a memory system that will grow with your needs. This
is a dynamic memory with the invisable on-board
refresh, and IT WORKS!

EXPAN DO 64 KIT (4116)j

Reg. Sale I
Price Price •

16K $249 $219

32K $324 $285 I

48 K $399 $355 •

64K $474 $415 I

Interfaces with Altair, IMSAI, SOL-8, Cromenco,
SBC-100, and others.

Bank Selectable
Phantom

Power 8VDC, ± 16VDC, 5 Watts
Lowest Cost Per Bit
Uses Popular 4116 RAMS

PC Board is doubled solder masked and has
silk-screen parts layout.

Extensive documentation clearly written
Complete Kit includes all Sockets for 64K
Memory access time: 375ns, Cycle time: 500ns.

No wait states required.

16K boundries and Protection via Dip Switches
Designed to work with Z-80, 8080, 8050 CPU’s

-'•h ; ■ : t r mi ■ lum? 1 1 JTT?mni I m iWfPfTTTlTi r

EXPANDOPROM

The ExpandoPROM can be populated with either the
2708 (IK) or the 2716 (2K) EPROMS, and may be
located on either 16K or 32K boundaries.

• S-100 Bus Compatible

• Expandable Read Only Memory from IK to 32K

• Each EPROM is Dip Switch Selectable

• Dip Switch for Addressing on 16K/32K Boundaries

• Dip Switch Selectable Wait States £

• Interfaces with Imsai, Altair, Sol-20 Cromemco/)

and SD SYSTEMS’ Z80 CPU Cards A / c

SDS-EXPANDOPROM KIT $136.00 I

SDS-EXPANDOPROM KIT $210.00^

SINGLE

BOARD

computer!

VDB-8024 VIDEO DISPLAY BOARD

With on-board Z80 Microprocessor

• S-100 bus Compatible

• Full 80 Characters by 24 Lines Display

• Characters Displayed by High Resolution 7 x 10
Matrix

• Composite or TTL Video Output

• Keyboard Power and Interface

• Forward and Reverse Scrolling Capability

• Blinking, Underlining, Field Reverse,

Field Protect and Combinations

• Full Cursor Control

• 96 Upper and Lower Case Characters

• 32 Special Character Set

• 128 Additional User Programmable Characters
(Optional)

• On-Board Z80 Microprocessor

• 2K Bytes Independent On-Board RAM Memory /> **'©

• Glitch-Free Display

SDS-VDB-8024 KIT $315.00 |

^SDS-VDB-8024 A&T $469.00 A

Z80 CENTRAL PROCESSING UNIT

• S-100 Bus Compatible • Z80 Microprocessor

• 2 Mhz or 4 Mhz Operation

• Power-On Jump to any 4K Boundary

• On-Board Socket for up to 2K PROM

• Front Panel Usage Optional • Optional Wait States

The MPB-100 can upgrade an existing S-100 8080
System with little or no necessary modifications. The
MPB-100 is additionally suited for some control ap-
plications. The PROM socket will accomodate a IK or
2K PROM plus the single voltage 4K PROM. Sal©

SDS-MPB-100 KIT $199.00

SDS-MPB-100 A&T $289.00^

PROM-100

Programming Board
for PROM Development

NEW

SD SYSTEMS’ PROM-100 is a versatile PROM pro-
gramming board offering complete EPROM program-
ming capability. The board operates on the industry
standard S-100 Bus. Support software verifies the
erasure of EPROM and verifies the loaded program.

SD SYSTEMS’ PROM-100 offers a support-software
listing with its operations manual.

• S-100 Bus Compatible

• Programs the Following EPROM s: 2708, Intel
2758, 2716, 2732 and Texas Instruments 2516

• Dip Switch Selection of EPROM type

• 25 VDC Programming Pulse Generated On Board

• Maximum Programming time: 16,384 Bits in
100 Seconds

• Power Requirement: +8VDC at 300 ma.;

+ 16 VDC atr 100 ma.; - 16 VDC at 60 ma.

• TTL compatible

• Software Provides for Reading of Object File
from SDOS, CP/M or PROM and Programming

into EPROM S^/

• Program Verification • Verification of Erasure/*... '©

• Zero Insertion Force Socket ''Cq

SDS-PROM-100 KIT $149.00

SDS-PROM-100 A&T $219.00

With On-Board RAM, PROM, CTC

• S-100 Bus Compatible

• Z80 Central Processing Unit

• 1024 Bytes of Random Access Memory

• 8K Bytes of PROM using 2716

• Parallel Input and Output Ports 0

• Four Channel Counter/Timer (Z80-CTC) >0

• Software Programmable Baud Rate Generator *y 'o

• No Front Panel Required for Operation

SDS-SBC-100 2MHZ KIT $219.00

SDS-SBC-100 2MHZ A&T $349.00

SDS-SBC-200 4MHZ KIT $259.00

SDS-SBC-200 4MHZ A&T $369.00 J |

PRIORITY ONE ELECTRONICS «

Terms:

Minimum

MINIMUM $2.50. Excess refunded. Just in case . please include your phone no.

Prices subject to change without notice.

We will do our best to maintain prices thru Dec 1979 qEM and Institutional

phone orders welcome (213) 894-8171, (800) 423-5633 inquiries invited.

Z80 STARTER KIT

A Complete Microcomputer On A Board

• Z80 CPU with 158 Instructions

• On-Board Keyboard and Display

• On-Board PROM Programmer for Single
Voltage PROMS (2716, 2758, TI2516)

• Kansas City Standard Cassette Interface

• Simple Key Controlled Audio Cassette Load
and Dump

• Expansion Provision for Mounting Two
S-100 Connectors (Sockets Not Included)

• Wire Wrap Area for Custom Circuitry

• Single Step through RAM or PROM

• Memory Examine and Change

• Port Examine and Change

• Z80 CPU Register and Change
2K Byte ZBUG Monitor in ROM
IK Bytes of RAM (Expandable to 2K Bytes)

A 4 Channel Hardware Counter/Timer (Z80-CTC)

Two Bi-Directional 8-Bit I/O Ports (Z80-P10)

Up to 5 Programmable Breakpoints
Switch Selectable PROM or Monitor Restart S*/
Vectored Interrupts provided by Z80-CTC and

SDS-Z80 STARTER KIT $219.00°®^

SDS-Z80 STARTER A&T $369.00

ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

LOOK FOR OUR HUGE AD IN JANUARY BYTE

HICKOK LX303 $74.95 HICKOK LX303 $74.95

# HICKOK

LX303

before

X-mas/

.5%, 3V 2 digit 19
Range DVM. Vi” LCD displays
runs 200 hrs on 1 battery. 10 Meg
Ohm Input. 1 yr. guarantee, made in
U.S.A., test leads included.

Available Accessories

RC-3 115V AC Adapter $7.50

CC-3 Deluxe Padded Vinyl

Carrying Case $7.50

VP-10 X10 DCV Probe Adapter/

Protector lOKv $14.95

VP-40 40 Kv DC Probe $35.00

CS-1 10 Amp Current Shunt $14.95

r *FREE

Just for Asking.

FREE BATTERY with your meter.

PART NO.

DE9P

DE9S

DE9C

DA15P

DA15S

DA15C

DB-25P

DB-25S

0651212-1

DB1226-1 A

DB1 10963-3

DC37P

DC37S

DC37C

OD50P

D050S

D050C

D20418-S

RS232 & “D” TYPE CONNECTORS *

Plug-Male S = Socket-Female C = Cover-Hood

PRICE
) 5-9

1.50 1.30
.05
.30
.00

3.20 3.00
1.60 1.45

2.90 2.60
3.75 3.65
1.65 1.40

1.90 1.60
1.80 1.55
3.95 3.80

DESCRIPTION

9 Pin Male
9 Pin Female
9 Pin Cover
15 Pin Male
15 Pin Female
15 Pin Cover
25 Pin Male
25 Pin Female

1 pc. Grey Hood

2 pc. Black Hood

/ ^M l l!l!i!i!i l i!l^ *j

\ pc. Grey Hood

37 Pin Male

10-24

1.20

1.95

1.15

1.80

2.80

1.30

2.50
3.40
1.20

1.50
1.35

/-■ » J.wo o.ou

^V.V.V.V.-^ STS S.S0

37 Pin Female
37 Pin Cover

50 Pin Male . . .

50 Pin Female ^Bpeeeoee ivvv' 7.50 7.20
50 Pin Cover 2.50 2.20

Hardware Set (2 pair) 100 .80

Connector for CENTRONICS 700 SERIES:

Amphenol 57-30360 for back of Centronics 700 Series printers
1-4- $9 00 5 up — $7.50

S-100 BUS EDGE CONNECTORS*

$4.00

S10O-WWG 50/100 Cont .125 ctrs. 3 LEVEL S100-STQ 50/100 Cont .125 ctrs. DIP
WIRE WRAP 025" sq posts on .250 spac- SOLDER TAIL on 250 spaced rows for
ed rows. GOLD PLATED VECTOR. IMSAI, CROMENCO mother

1.4 5.9 10-24 boards GOLD plated

13.75 1-4 5-0 10-24

$4.10 $3.80 *3.50

S100SE 50/100 Cont .125 Ctrs. PIERCED S100ALT 50/100 Cont 125 ctrs. DIP
SOLDER EYELET Tails GOLD SOLDER TAIL on 140 spaced rows for

1 4 M 10 24 ALTAIR motherboards, GOLD plated.

$5.00 $4.50 $4.00 1-4 5-9 10-24

$4.50 $4.25 $4.00

Other Popular Edge Connectors

D2244-5WW 22/44 Cont .156 ctrs.WIRE D2244-5SE 22/44 Cont .156 Ctrs.PIERCED
WRAP tails GOLD. SOLDER EYELET tails GOLD plated.

1-4 5-9 ia24 14 5-9 10-24

$3.95 $3.70 $3.40 $3.00 $2.60 $2.20

CG 1 (MSA) Style Card Guides 5/$1.00

See our July Ad for many other connectors.

$4.75

3 LEVEL GOLD WIRE WRAP SOCKETS*

Sockets purchased in multiples of 50 per type may be combined for best price.

1-9

10-24

25-99 100-249 250-999

8 pin

.40

.36

.34

.31

.27

14 pin

.44

.43

.41

.39

.37

16 pin

.55

.47

.45

.41

.39

18 pin

.70

.60

.55

.50

.45

20 pin

.90

.80

.75

.65

.62

22 pin

.95

.85

.80

.70

.65

24 pin

.95

.85

.80

.70

.65

28 pin

1.25

1.15

1.00

.95

.90

40 pin

1.65

1.45

1.35

1.20

1.10

All sockets are GOLD 3 level closed entry. 2 level Tail Low
Profile, Tin Sockets and Dip Plugs available. CALL FOR QUOTATION.

Dapple plugboard

Vector 4609 Peripheral Interface Plugboard for construction of custom circuits.
Plug compatible with Apple II, Commodore PET and Super Kim microcomputers
Three connectors, in addition to the standard 25/50 system bus, are available for
input/output. A 20/40-contact card-edge connector, fabricated on the rear of the
board, mates with a 3-M type ribbon connector. Alternatively, a right-angle
solder-tail header may be positioned in this same location. The Model 4609 also
accomodates the miniature SIP-type connectors which may be placed on the
periphery or in mid-board. 1.4 5.9 10-24

$21.50 $19.36 $17.26

7520 APPLE EXTENDER CARD $24.95

is 12

8803

MOTHER
BOARD FOR

tantalum cawci-
wstof *5, +12.

—12 Duses and msu

lated mounting spacers cmn RlK

• Wiring side slwm Com- i,UU BUJ >

poneii nae Dare epo*y MICRO-

glass wilt, while markings lor COMPUTERS

component ocations

• GtOepoiy glass tioard with 2 ounci
copper, solder plated and 03S diame-
ter holes lor leads

• Soloer mask wiin solder windows on
etched circuits to avoid accidental short
circuits

• Mounts 1 1 receptacles with 100 contacts (2
rows) on 125 centers with 250 row spacing.

Vector pal number R681 2. or mounts tOrecep
tacles plus interconnections to smaller mother board
tor expansion

i/ectffi

Plugboards

, Price:
$29.50

8800V

Universal Microcomputer/processor
plugboard, use witn S-100 bus Com-
plete with heat sink & hardware 5.3" x
10 x 1/16

1-4 5-9 10-24

$19 95 $17.95 $15.96

8801-1

Same as 8800V except plain: less power
buses & heat sink

1-4 5-9 10-24

$15.22 $13.79 $12.18

\r

3682 9.6” x4.5”
$12.97

3682-2 6.5” x 4.5”
$9.81

Hi-Density Dual-In-Line
Plugboard for Wire Wrap
with Power & Grd. Bus
Epoxy Glass 1/16” 44
pin con. spaced .156

3677 9 6” x 4.5’

$10.90

3677-2 6.5” x 4.5”

$9.74

Gen. Purpose D.I.P.
Boards with Bus Pattern
for Solder or Wire Wrap.
Epoxy Glass 1/16” 44
pine q. spaced .156

mm* 3 *
mm

3662 6.5” x 4.5”

$8.95

3662-2 9.6” x 4-5”

$11.45

P pattern plugboards for
IC's Epoxy Glass 1/16”
44 pin con. spaced .156

3690-12
CARD EXTENDER

Card Extender has 100 con-
tacts 50 per side on .125
centers-Attached connec-
tor-is compatible with
S-100 Bus Systems. $25.83
3690 6.5” 22/44 pin .156
ctrs. Extenders $13.17,

S

14 & 16 PIN
GOLD 3 LEVEL
WIRE WRAP
SOCKES*

14 - G3 100 for
$36.00
16 - G3 100 for
$37.00

50 of each for $38.00

1/16 jkftcR BOARD
.042 dia holes on
0.1 spacing for IC’s

Phenolic

PRICE

PART NO.

SIZE

1-9 10-19

64P44XXXP

4.5X6.5”

$1.56 $1.40

169P44XXXP

4.5x17”

$3.69 $3.32

Epoxy Glass

64P44

4.5X6.5”

$1.79 $1-61

84P44

4.5x8.5”

$2.21 $1.99

169P44

4.5x17”

$4.52 $4.07

169P84

8.5x17”

$8.83 $7.95

TRS-80/APPLE

MEMORY EXPANSION KITS
4116's RAMS % .

^ from Leading Manufacturers

(16Kx1 200/250ns)

* 8 for $75.00

Add $3.00 for programming Jumpers

PRICE: $18.98

3 1 5 — S same as 315
but with 14" bar to
accomodate "S100"
boards.

PRICE $19.98

> to^T^S^^J<©^boar^

VISE

WAS*

PRICE: $13.49

HORIZONTAL
JAW VISE HEAD

PRICE: $14.49

PRICE: $13.49
VACUUM BASE

PRICE:$14.49
PANAVISE TILTS, TURNS, AND \ ‘£1*
ROTATES TO ANY POSITION. 5-'**
IT HOLDS YOUR WORK
. EXACTLY WHERE YOU WANT IT.

PRICE: $18.49

PRICE: $14.49

WRAP POST

for .042 dia. holes

I (all boards on this page) '
T44/C pkg. 100 . . $ 2.34
T44/M pkg. .

1000 $14.35 V I

A-13 hand installing

tool >4.19 A

DEALERS
CALL FOR

PRICING

3M SCOTCH* BRAND
DISKETTES

740-OP 1/single Soft-1 BM
740/2-OP 2/single Soft-IBM
740- 32P 1/single 32

744-OK
744-10K
744 16K

$39 95
$75.00
$39.95
$75.00
$59.00

1/single Soft (TRS-80) $51.00*
1/single Soft/10 $51.00*
1/single Soft/16 $51.00*

•Price includes Kas ette/10 Storage Box
a $5.00 Value (TRS-80)

"DON T SETTLE FOR ANYTHING
LESS THAN SCOTCH"

MEMORY MEMORY

2102LIPC Low Power 450ns in lots of 25 $1.10
2102AL-2 Low Power 250ns in tots of 25 $1+25
211 4-3 L 1 Kx4 300 ns Low Power 8/$50.00

5257-3 L 4Kx1 300ns Low Power 8/$50*Q0
2708 8K 450ns EPROM 8/65.00 $9.00
2716 16K 5 Voli Only EPROM $40+00

CALL FOR QUANTITY PRICES

IM-10A List $89.00
SPECIAL
$56.95 with tube

Perfectly balanced fluorescent lighting
with precision magnifier lens. Tough
thermoplastic shade. Easy lens re-
moval. New wire clip design permits
easy installation and removal of
fluorescent tube. Comes with plastic
shield to protect tube from soiling and
damage.

Colors: Gray, Black, and Chocolate Brown.
Comes with one 22 watt T-9 Clrcline fluores
cant lube. 3jJlQ£ t»f l ens.

ORDER TOLL FREE

1 - 800-423 56331

: CA.. AK., HI.,

(213)894-8171

PRIORITY ONE I ELECTRONICS

16723K Roscoe Blvd. Sepulveda, CA 91343

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales tax.

Minimum order $10.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling,
MINIMUM $2.50. Excess refunded. Just in case . . . please include your phone no.

•SOCKET end CONNECTOR .^l 068 SUb i eCt '° Chan 9« Wllh0Ut " 0tiCe -

prices Cased on gold, not We will do our best to maintain prices thru Dec. 1979 OEM and Institutional

exceeding u75.oo pe- or phone or( j ers welcome (21 3) 894-81 71 , (800) 423-5633 Inquiries Invited.

TEST

EQUIPMENT
CALL FOR
X-MAS PRICES

ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

■

$74.95 HICKOK LX303 $74.95 HICKOK LX303 $74.95*

P.O. Box 4430S Santa Clara, CA 95054

ATTENTION ELF OWNERS: QUEST SUPER BASIC

Quest, the leader in inexpensive 1802 systems
announces another first. Quest is the first com-
pany worldwide to ship a full size Basic for 1 802
systems. A complete function Super Basic by
Ron Cenker including floating point capability
with scientific notation (number range ±.17E 38 ),

32 bit integer ±2 billion, Multi dim arrays, String
arrays, String manipulation, Cassette I/O, Save
and load, Basic, Data and machine language pro-
grams and over 75 Statements, Functions and
Operators.

Easily adaptable on most 1802 systems. Re-
quires 12K RAM minimum for Basic and user
programs. Cassette version in stock now. ROM

RCA Cosmac Super Elf Computer $106.95

versions coming soon with exchange privilege
allowing some credit for cassette version.

Super Basic on Cassette $40.00

Tom Pittman’s 1802 Tiny Basic Source listing
now available. Find out how Tom Pittman wrote
Tiny Basic and how to get the most out of it.
Never offered before. $19.00

S-100 Slot Expansion $9.95

Coming Soon: Assembler and Editor; Elf II
Adapter Board. High resolution alpha/numerics
with color graphics expandable up to 256 x 192
resolution for less than $100.

1 6K Dynam. RAM bd. expand. 32K; less than $150.

Compare features before you decide to buy any
other computer. There is no other computer on
the market today that has all the desirable bene-
fits of the Super Elf for so little money. The Super
Elf is a small single board computer that does
many big things. It is an excellent computer for
training and for learning programming with its
machine language and yet it is easily expanded
with additional memory, Full Basic, ASCII
Keyboards, video character generation, etc.
Before you buy another small computer, see if it
includes the following features: ROM monitor;
State and Mode displays: Single step; Optional
address displays; Power Supply; Audio Amplifier
and Speaker; Fully socketed for all IC’s; Real cost
of in warranty repairs; Full documentation.

The Super Elf includes a ROM monitor for pro-
gram loading, editing and execution with SINGLE
STEP for program debugging which is not in-
cluded in others at the same price. With SINGLE
STEP you can see the microprocessor chip opera-
ting with the unique Quest address and data bus
displays before, during and after executing in-
structions. Also, CPU mode and instruction cycle
are decoded and displayed on 8 LED indicators.
An RCA 1861 video graphics chip allows you to
connect to your own TV with an inexpensive video
modulator to do graphics and games. There is a
speaker system included for writing your own
music or using many music programs already
written. The speaker amplifier may also be used

A 24 key HEX keyboard includes 16 HEX keys
plus load, reset, run, wait, input, memory pro-
tect, monitor select and single step Large, on
board displays provide output and optional high
and low address There is a 44 pin standard
connector slot for PC cards and a 50 pin connec-
tor slot for the Quest Super Expansion Board.
Power supply and sockets for all IC's are in-
cluded in the price plus a detailed 127 pg. instruc-
tion manual which now includes over 40 pgs. of
software info, including a series of lessons to
help get you started and a music program and
graphics target game.

Many schools and universities are using the
Super Elf as a course of study. OEM’s use it for
training and research and development.
Remember, other computers only offer Super Elf
features at additional cost or not at all. Compare
before you buy. Super Elf Kit $106.95, High
address option $8.95, Low address option
$9.95. Custom Cabinet with drilled and labelled
plexiglass front panel $24.95. Expansion Cabinet
with room for 4 S-100 boards $41.00. NiCad
Battery Memory Saver Kit $6.95. All kits and
options also completely assembled and tested.
Questdata. a 12 page monthly software publica-
tion for 1802 computer users is available by sub-
scription for $12.00 per year.

Tiny Basic Cassette $10.00, on ROM $38.00,
original Elf kit board $14.95. 1802 software;
Moews Video Graphics $3.50. Games and Music
$3.00, Chip 8 Interpreter $5.50.

to drive relays for control purposes

Super Expansion Board with Cassette Interface $89.95

This is truly an astounding value! This board has
been designed to allow you to decide how you
want it optioned. The Super Expansion Board
comes with 4K of low power RAM fully address-
able anywhere in 64K with built-in memory pro-
tect and a cassette interface. Provisions have
been made for all other options on the same
board and it fits neatly into the hardwood cabinet
alongside the Super Elf. The board includes slots
for up to 6K of EPROM (2708, 2758, 271 6 or Tl
2716) and is fully socketed. EPROM can be used
forthe monitor and Tiny Basic or other purposes.

A IK Super ROM Monitor $19.95 is available as
an on board option in 2708 EPROM which has
been preprogrammed with a program loader/
editor and error checking multi file cassette
read/write software, (relocatible cassette file)
another exclusive from Quest. It includes register
save and readout, block move capability and
video graphics driver with blinking cursor. Break
points can be used with the register save feature
to isolate program bugs quickly, then follow with
single step. The Super Monitor is written with

subroutines allowing users to take advantage of
monitor functions simply by calling them up.
Improvements and revisions are easily done with
the monitor. If you have the Super Expansion
Board and Super Monitor the monitor is up and
running at the push of a button.

Other on board options include Parallel Input
and Output Ports with full handshake. They
allow easy connection of an ASCII keyboard to the
input port. RS 232 and 20 ma Current Loop for
teletype or other device are on board and if you
need more memory there are two S-100 slots for
static RAM or video boards. Also a IK Super
Monitor version 2 with video driver for full capa-
bility display with Tiny Basic and a video interface
board Parallel I/O Ports $9.85, RS 232 $4.50,
TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pin
connector set with ribbon cable is available at
$12.50 for easy connection between the Super
Elf and the Super Expansion Board.

Power Supply Kit for the complete system (see
Multi-volt Power Supply below).

Multi-volt Computer Power Supply

8v 5 amp, ±18v .5 amp, 5v 1.5 amp, -5v
.5 amp, 12v .5 amp, -12 option. ±5v, ±12v
are regulated. Kit $29.95. Kit with punched frame
S37.45, $4.00 shipping. Woodgrain case
S10.00, $1.50 shipping.

60 Hz Crystal Time Base Kit $4.40

Converts digital clocks from AC line frequency
to crystal time base. Outstanding accuracy. Kit
includes: PC board, 1C, crystal, resistors, ca-
pacitors and trimmer.

TERMS: $5.00 min. order U.S. Funds, Calif residents add 6% tax.
BankAmericard and Master Charge accepted.

Shipping charges will be added on charge cards.

7409N .

741 ON

7414N

7420N

7422N

7430N

7442N

7445N

7447N

7448N

7450N

7474N

7475N

7485N

7489N

7490N

7492N

7493N

7495N

741 0GN

74107N

74121 N

74123N

741 25N

741 45N

74150N

741 51N

74154N

741 57N

741 61 N

74162N

741 63N

741 74N

741 75N

74190N

74192N

7419344

74221 N

74298N

74365N

74366N

74367N

74LSOO TTl

74LSOON .35
741S02N .35

74LS04N 35

74LS05N .35

74LS08N .35

74LS10N .35

74LS13N 55

74LS14N 1.10

74LS20N 35

74LS22N .35

74LS28N .41

74LS30N .35

74LS33N .75

74LS3BN .55
74LS74N 1.25

74LS75N 1 00

74LS90N 65

74LS93N 70

74LS95N 1 10

74LS107N 45

741S112N 45

74LS113N 35

74LS132N 89

74LS136N 45

74LS151N 85

74LS155N .85
74LS157N .85

74LS162N 1.15
74LS183N 1.15
74LS174N 2.00
74LS190N 1 06
74LS221N 1 95
74LS258N 67

74LS367N 1.35

LINEAR

CA3045 .90

CA3046 1.10

CA3081 1.80

CA3082 1 90

CA3089 2.95

I.M301AN/AH.35
LM305H .87
LM307N .35
LM308N 89
LM309K 1.50
LM311H/N .90
LM317T/K 3 75
LM31B 135

LM320K-5 1.50

LM323K-5 5.95

LM320K-12 150
LM320K-15 150
LM320T-5 1.60

LM320T-8 160

LM320T-12 1.50
LM320T-15 160
LV1324N 115

LM339N 155

IM340K-5 1 35
LM340KB 1 .35
LM340K-12 1.35
LM340K-15 1.35

LM340K-24 1,35
LM340T-5 1.25

LM340T-8 1.25

LM340T-12 1 25
LV340T-15 1.25
LM340T-18 1.25
LM340T-24 1.25
LM343H 4 50
LM350 7.50

LM370 1.15

LM377 3.00

LM379 5 00

LM380N 1.00
LM381 1.60

LM382 1.60

LM703H .40
LM709H .28
LM723H/N 50
LM733N 6 ?
LM741CH 35
LM741N .32
LM747WN .75
LM748N 35
LM1303N 1.75

LM1304 1.10

LM1305 1.27

LM1307 2.00

LM1310 2.75

LM1458 47

LM1800 1.75

I.M1812 7.5C

LM1889 3.00

LM2111 175

LM2902 1 50

IM3900N 6 C
LM3905 1.75

LM3909N .89

MCI 458V .50

NE550N 1 00

NE555V .39
NE55SA 85
NE565A 100
NES 66 V 1.50
NE567V 1.00
NE570B 5.00
78105 .60

78L08 .60

78M05 .85

75108 1.75

75491CN .50

75492CN .55

75494CN .89

A to 0 CONVERTER

8036B 4.50

8700 CJ 13 95

8701CN 22 OO

8750CJ 13.95

10130 9.95

9400CJV/F 7 40
ICL7103 9.50

ICL7107 14.25

CMOS

C034001 Fair. .50
CD4000 .16

C 04001 .28

C04002 28

CD4006 1.10

CD4O07 .28

CD400B 28

CD4009 .45

CD4010 45

CD4011 28

CD4012 28

CD4013 39

CD4014
CD4015
C04016
CO4017
CO4018
CO4019
C04020

CD4021

CD4022 .

CD4023

CD4024

C04025

CO 4026

C04027

CD4028

CD4029

CD4030

C04035

CD404C

CD4342

CD4043

C04044

CO 4046

C04049

C04050

C040S1 •

CD4O60

CD4C66

CD4068

CD4069

CD4070

CD4071

CD4072

CO4073

CO4075

C04076

C04078

CD4081

C04082

CD4116

C04490

CD4507

CD4508

804510

CD4511

CD4515

C04516

CD4518

C04520

CD4527

CD4528

C04553

CD4S66

CO-4583

C04S85

C040192

74C0C

74C04

74C10

74C14

74C20

74C30

74C46

74C74

74C76

74C90

74C93

74C154

74C160

74C175

74C192

74C221

74C905

74C906

74CSM

74C922

74C923

74C925

74C926

74C927

21102-1
21F02
2104A-4
2107B-4
2111-1
2112-2
2114L-1
21141-3
4116
251 3B
MM5262
MMS2M
MM532G
MMS33C
P04110-3
PD4110-4
P5101L
4200A
82S26
91L02A
H 00165-5
MM57100
GIAY38500-1 9
MCM6571A 9.95

10 per type 03 1000 per lype .012

5Q 25 per type .025 350 p*ece pack
3 75 100 per type 015 5 per lype 6 75

375 vy wan 5% per type .05

3J5 KEYBOARDS

8 75 55 i, ey ASCII keyboard kit S67.50

8 75 folly assemoled 77.50

2 90 53 ley ASCII keyboard kit 60.00

2.90 Fully assembled 70.00 Enclosure 14.95

LEDS

2,50 Red T018 15

2,75 Green. Yellow T018 .20

lu ,,, 4 M Jumbo Red .20

100 oin edoe WW 5.25 Green. Orange, Yellow Jumbo ,25

iuu pin eope a Ciipllle LED Mounting Clips 8/SI. 25

(specify red. amber, green, yellow, dear)

1C SOCKETS

Solder Tin Low Profile CONTINENTAL SPECIALTIES in slock

4.50

8 .15 22 . 30

14 .14 24 .35

16 .16 28 .4?

3.50 18 27 36 58

10.00 20 . 29 40 .57

16.00 2 levw 14 pin «rw 20

CLOCKS
MM5314
MM5315
MM5368
MM5841
MM5865
CT7001
CT7010

CT7015 . ._

MW53/5A/VN 3 90
MM537SAG/N 4.90
7205 16.50

7207

not

7209

WIRE WRAP LEVEL 3
3 90 PIN PIN

4.00 14 .32 24 86

2.10 16 33 28 1.00

14.45 18 .57 40 1.23

5.80

8.95 CRYSTALS

7 2S 1 MHz

2 MHz
4 MHz

5 MHz

7.50 10 MHz

15.95 18 MHz

4 .95 20 MHz

3.75 32 MHz

DSO056CN 3 75 32768 MHz

»*3,04 VMK*

MICROPROCESSOR 2.0100 MHz

6600

6802
B08DA

SPECIAL PRODUCTS

MM5865 Stopwatch Timer 9.00
PC board 7.50

Switches Mom. Pushbutton .27
3 pos. side .25

Encoder HO0165-5 6.95

3 Digit Universal
Counter Board Kit
Operates 5-18 VoK DC to 5 MHz
typ. .125' LEO display 18.50
Paratronics 10OA Logic

$224.00

$229.00

8396

8097

8098
8T09
8 TIC
8T12
8T20
8T23
8*24
8T25
8T26
8T28
8T97
8198

8 Analyzer Kl

4,2 Model 10 Tngger

, Expander Kit

, Model 150 Bus

2 qt Grabber Kit $369 00

2 m Sinclair 3'/> Digil

2 m Multimeter $59.95

] 22 Clock Calendar Kit $23.95

. 22 2.5 MHz Frequency Coanter

12 Kit S37.50

, r n 30 MHz Frequency Counter

4 50 “ * 47 ’ 75

4.50 TRANSFORMERS

4.50 6 V 300 ma 3.25

"* 12 VoK 300 ma transformer 1.25

12.6V CT 600 ma 3.75

12V 250 ma wall plug 2.95

12V CT 250 ma wall plug 3.50

24V CT 400 ma ’ “

10V 1.2 amp wall plug
12V 6 amp

12V 500 ma wall plug
12V 1 amp wall plug o.ov

SI 2.50 12V 3 amp wall plug 8 50

’5 50 DISPLAY LEDS

n 50 MAN1 CA 270 2.90

6 95 MAN3 CC 125 39

MAN72/74 CA/CA 300 1.00

OL704 CC 300 1.25

1861P 11 50 D Connectors RS232 122122

COP1802CD 19 95 DB25P 2.95 §^727/728 CA^ 500 90

SKf &S K? t“ 8™ cc :l«l !:«

h?° in ESSi&o; coS S ,3

2 10 FND503/51O CC/CA .500 90

3 10 FN0600I807 CC/CA .800 2.20

8085

Z80

Z80A

8212

8214

8216

8224

8228

8251

8253

8255

8257

8259

1802CP

plas.

18020P

3.95
4.85
12 95

17.50 2.097152 MHz

18.75 2.4576 MHz

8 95 3.2768 MHz

27.00 5.0688 MHz

14.75 5.185 MHz n og

19 75 5.7143 MHz 4.50

2.90 6 5536 MHz 4 50

8 00 14.31818 MHz 4 25

2.90 18.432 MHz 4 .50

2 90 22 1184 MHz 4.50

5.35

8 50

15 00 KEYBOARD ENCODERS

9 25 AY5-2376

19 50 AYS-3600

19 50 74C922

74C923

13.95 H00165-5

17 95

1 30 MOS/MEMORY

45 RAM

1.05 2101-1 3.95

.94 2102-1 .95

.45 Z102AL-4 1.25

1 02 2102AN-2L 1.60

21 L 02-1 1.18

6502

6504

6522

UART/FIFO

AYS-1013

AY5-1014

3341

PROM

1702 A

2708

2716T1

2716 Intel

2732

2758

8741A

8748

8748-8

8755A

NS2S23

TRANSISTORS

2NI893
550 2N222A

7 50 2N2369

695 2N2904A

2N2907A
„ „ 2N3053

3.95 2N3638

10 50 2N3643

29 50 2N3904

48.00 2N3906

115.00 2N3055

22.50 2N4400

85 00 2N4401

75.00 2N4402

60.00 TIP31

65.00 TIP33A

2.95

3 digit Bubble

4 digit Bubble
0G8 Fluorescent
OGIO Fluorescent

5 digit 14 pin display
NSN69 9 digit c splay
7520 Claire* photocells
TIL311 •

80

MAN 3640
MAN46'0
MAN4640
MAN4710
MAN4740
Si MAN6640
£ MAN6710

73 MAN6740

// MA1002A

1 00 MA1012A

102P3 transformer

39
9.50
CC .30 1 10
CA 40 1.20
CC 40 1.20
CA 40 .95

CC 40 1.20
CC .56 2.95
CA .60 1.35
CC 60 1.35
8.95
8.95

Rockwell AIM 65 Computer

6502 based single board with full ASCII keyboard
and 20 column thermal printer. 20 char, al-
phanumeric display, ROM monitor, fully expand-
able. $375.00 . 4K version $450.00 . 4K Assem-
bler $85.00, 8K Basic Interpreter $100.00.
Power supply assy, in case $60.00. AIM 65 in
thin briefcase with power supply $485.00.

Not a Cheap Clock Kit $14.95

Includes everything except case. 2- PC boards.
6-. 50" LED Displays. 5314 clock chip, trans-
former, all components and full instructions.
Orange displays also avail. Same kit W/.80"
displays. Red only. $21.95 Case $11.75

Video Modulator Kit $8.95

Convert your TV set into a high quality monitor
without affecting normal usage. Complete kit
with full instructions.

S-100 Computer Boards

8K Static RAM Kit Godbout $135.00

16K Static RAM Kit 265.00

24K Static RAM Kit 423.00

32K Dynamic RAM Kit 310.00

32K Static RAM Kit $475.00

64K Dynamic RAM Kit 470.00

8K/16K Eprom Kit (less PROMS) $89.00
Video Interface Kit $139.00

Motherboard $39. Extender Board $8.99

79 1C Update Master Manual $35.00

Complete 1C data selector, 2500 pg. master refer-
ence guide. Over 50,000 cross references. Free
update service through 1979. Domestic postage
$3.50. No foreign orders.

Auto Clock Kit $17.95

DC clock with 4-. 50" displays. Uses National
MA-1012 module with alarm option. Includes
light dimmer, crystal timebase PC boards. Fully
regulated, comp, instructs. Add $3.95 for beau-
tiful dark gray case. Best value anywhere.

Stopwatch Kit $26.95

Full six digit battery operated. 2-5 volts.
3.2768 MHz crystal accuracy. Times to 59
min., 59 sec., 99 1/100 sec. Times std., split
and Taylor. 7205 chip, all components minus
case. Full instructions.

NiCad Battery Fixer/Charger Kit

Opens shorted cells that won't hold a charge
and then charges them up, all in one kit w/full
parts and instructions. $7.25

PROM Eraser

Will erase 25 PROMs in 15 minutes. Ultra-
violet, assembled $34.50

Hickok 3Vz Digit LCD Multimeter

Batt/AC oper. O.Imv-IOOOv. 5 ranges. 0.5%
accur. Resistance 6 low power ranges 0.1
ohm-20M ohm. DC curr. .01 to lOOma. Hand
held, \ k" LCD displays, auto zero, polarity, over-
range. $69.95.

Digital Temp. Meter Kit $34.00

Indoor and outdoor. Switches back and forth.
Beautiful. 50" LED readouts. Nothing like it
available. Needs no additional parts for com-
plete, full operation. Will measure -100° to
+200°F, tenths of a degree, air or liquid.
Beautiful woodgrain case w/bezel $1 1 .75

FREE: Send for your copy of our NEW 1979
QUEST CATALOG. Include 28c stamp.

North Star Horizon

1 .4 megabyte computer system —

Now double density or quad density (double headed, double sided

minifloppy disk drive)

The NORTH STAR HORIZON® is a price-performance
leader in S-100 systems. It features a 4 MHz CPU board
and double-density -disk controller board. All Horizons*
now come with two serial RS232C ports, a parallel port,
all 12 edge connectors, and an interface cable for
connection to an external drive. Horizons are available as
single-drive units (Horizon 1) or dual-drive units (Horizon
2). Drives can be double density or double-sided (quad
density). A Horizon 2 with two external quad drives gives
the user 1 .4 megabytes of on-line storage. The Horizon
comes with a DOS and North Star Extended Disk BASIC.
A CP/M operating system is only $129.

Just add a terminal and you have a complete and
extremely flexible computer system. For example, either
the INTERTUBE II or Perkin-Elmer BANTAM 550 video
terminals are only $799 additional from MiniMicroMart.

* A few 16K Horizons still available
as low as $1349!

HORIZON 1 — now fully configured (all
options)

32K double-density, Kit, List $1999 .... $1684
Assembled and Tested, List $2315 . . $1959

32K, quad-density, Kit, List $2199 1869

Assembled and Tested, List $2565 . . 2174

HORIZON 2 — now fully configured — all
options

32K, double-density, Kit, List $2399 . . . $2034
Assembled and Tested, List $2765 . . 2339

32K, quad-density, Kit, List $2779 2359

Assembled and Tested, List $3215 . . 2719

Additional 16K RAM with parity

Kit (RAM-16A), List $399 $329

Assembled and Tested, List $459 389

Additional 32K RAM with parity

Kit (RAM-32), List $599 $499

Assembled and Tested, List $659 549

Intertec INTERTUBE II List $995 . . . $799
$499

T.l. 81 0 PRINTER (basic unit)

with RS232 serial interface, List $1895 $1695

with RS232 serial and parallel interfaces 1735

ANADEX
DOT MATRIX
PRINTER

List $995

ONLY
$895

NOTE: Horizons may be ordered for future delivery with only 10% deposit.

SHIPPING , HANDLING and INSURANCE: Add $15 for Horizons , $10 for terminals or An ad ex printer. T.l. printer shipped freight collect.
All prices are subject to change and offers are subject to withdrawal without notice. Credit card purchases are 2% higher.

- WRITE FOR FREE CATALOG -

MiniMicroMart, Inc.

^M61

1618 James Street, Syracuse, NY 13203 (315) 422-4467 TWX 710 541-0431

Terminals and Printers

for every application . . .

Complete

Computer!

SUPERBRAIN® by Intertec

• Totally self-contained in a single box

• 32K ; 48K ; or 64K Version

• Uses two Z-80 CPU's

• Commercial-type terminal with
1 2" monitor (like the Intertube)

• Dual double-density minifloppies
w/360 Kilobytes of storage capacity

• I/O ports included

• Expandable (if needed) with an
external S-100 bus interface

• Comes with CP/M™ operating
system

• Extensive software support

Sells for well under $3,000!

Call for price and delivery.

BANTAM 550

from PERKIN ELMER

Small in size, light in weight, and low in
price - but on top of the list in features
and performance.

• Upper and lower case

• Full 24 x 80 format

• Sharp 7 x 10 dot matrix

Get everything you want without paying for
things you don't need - List: $996

NOW FROM

US AT

$799

Add $20 for
anti-glare
CRT

ANADEX 80-COLUMN
DOT MATRIX PRINTER

Complete upper and lower case ASCII char,
set, bi-directional at 84 lines/min. Features
RS232 20/60 mil current loop and Centronix
parallel interface. Ideal for use with TRS-80,
Sorcerer, Cromemco, and North Star systems.

OUR PRICE ONLY $895

INTERTUBE II by Intertec

• 12" Display

• 24 x 80 format

• 18-key numeric keypad

• 128 upper/lower case ASCI I characters

• Reverse video, blinking

• Complete cursor addressing and control

• Special user-defined control function keys

• Protected and unprotected fields

• Line insert/delete and character insert/

delete editing

• Eleven special line drawing symbols

OUR PRICE $799

IP-440 PAPER TIGER

IP-440 Basic Unit, List $995 $895

IP-440 w/Graphics Option, incl. Buffer
List $1194 $1069

I P-1 25 w/1 2 1 0 Option * , List $838 754
TRS-80 Cable 45

* 1210 Option is expanded and compressed print

T.1.810

Bi-directional

150 cps
Logic-
Seeking

Adjustable
Tractor C a // for our low , low prices

DECwriter II $1490

Teletype 43 Printers starting at $880
Lear Siegler ADM3A $849

NEC spiniiinter M

The Fantastic Letter-Quality
Printer at 55 cps

-CALL FOR PRICES —

CENTRONICS PRINTERS

730 New, friction, & tractor $ 895

779 (60 cps) - same as TRS-80 printer $ 979
with Tractor $1049

702-1 (120 cps, bi-directional) $1995

703 (185 cps, bi-directional) $2395

SHIPPING , HANDLING , & INSURANCE: Intertube , Bantam 550, Anadex, IP-125/225, Teletype
43's, Hazel tine 1500, and A DM3 A can be shipped by UPS. Heavier printers shipped air or truck,
freight collect.

Prices quoted reflect cash discounts. Credit cards only 2% higher. All prices subject to change and
all offers subject to withdrawal without notice.

— WRITE FOR FREE CATALOG —

MiniMicroMart, Inc.

1 61 8 James Street, Syracuse NY 13203 (315)422-4467 TWX 71 0-541 -0431

~ $£LECr#OA//C$

Does It again .... high quality Sylvania monitors at the lowest prices ever. These
monitors have been thoroughly checked and guaranteed.

MONITORS

12” black & white monitor. Wide band, will display
80 x 24 char. 10K or 75Q input impedance, com-
posite video input. Transformer power supply.

Shpt. Wt. 30#

Price: $45.00 ea.

Used with all computers such as: TRS-80, Apple,
and many others.

Complete manual $3.00

KEYBOARDS

51 key typewriter style keyboard, with case, not en-
coded. Single contact keys
Shpt. Wt. 10#

Price: $10.00 ea.

CABLES

5’ RG/59U cable with PL259 connector on one end.
Price: $1.00 ea. 6/$5.00

24” RG/59U cable with PL 259 connector on one
end, BNC on other end.

Price: $1.00 ea. 6/$5.00

SPECIAL

Microprocessor Chips #6502
Price: $6.00 ea. or 2/$10.00

CENTRONICS 101 A

• Model 101A, 60 to 200 lines/minute

• 165 characters/second

• 132 characters/line

• 9 x 7 dot matrix pattern

All models feature fixed vertical/horizontal registration; remote
select/deselect; elongate bold face characters (line by line); ver-
tical format unit; two channel VFU; prints originals plus four
copies; 8 bit ASCII parallel data input; paper runaway inhibit;
audio alarm; printing methods include impact character by char-
acter one line at a time.

Excellent condition guaranteed $550.00
Stand for above $25.00

DIGITAL DISPLAY BOARDS

6 digit numeric display boards with 6 FND 507.
Common anode displays and 10 red LED’s. With
drivers & logic for multiplexed operation.

Price: $5.00 ea. or 6/$25.00

REGULATED DC POWER SUPPLIES
MFGS. LAMBDA 8. NORTH

VOLTS

-AMPS

WT.

PRICE

5

74

62#

$40.00

5

31

40

35.00

5

16

18

30.00

5

10

18

25.00

5

4

7

20.00

5

13

20

30.00

5

20

30

35.00

• Test Equipment

• Power Supply Components

• Power Supplies

• Communication Equipment

• Pulse Equipment

ALL ITEMS ARE REMOVED FROM EQUIPMENT

$£l£Cr#Ofi//C$

TELEPHONES:
Area Code 215
HOward 8-4645
HOward 8-7891

1206 S. Napa Street • Philadelphia PA 19146

WAREHOUSE

1206- 18 S. Napa Street
1201-49 S. Patton Street

1207- 25 S. Napa Street

Penna. resident please add 6% sales tax. ALL PRICES ARE F.O.B. our warehouse, Phila. PA. AM>merchandise accurate as to
description to the best of our knowledge. Your purchase money refunded if not satisfied. Min. order $10.00.

206 Microcomputing January 1980

ADVANCED 1

COMPUTER

ODUCTS

THE FIRST TO OFFER PRIME PRODUCTS TO THE HOBBYIST
AT FAIR PRICES NOW LOWERS PRICES EVEN FURTHER!

1. Proven Quality Factory tested products only, no re tests

or fallouts. Guaranteed money back. We stand behind our products.

1979 CATALOG NOW AVAILABLE.

Send $1 .00 for your copy of the most complete catalog of computer products. A must

RAM BOARDS _

S-100 32K (uses 2114)

ASSEMBLED Kit 6 [/%*> P*

450ns. 599.00 450ns. 539.95

250ns. 699.95 250ns. 599.95

Bare Board 49.95

Bare Board w/all parts less mem. 99.95

S-1 00 1 6K (uses 2114) KIT (exp. to 32K)

450ns.

250ns.

ASSEMBLED
450ns. 325.00

250ns. 375.00

Bare Board 49.95
LOGOS I 8K
ASSEMBLED
450 ns. 169.95 KIT 450ns. 125.95

250ns. 189.95 250ns. 149.95

Bare PC Board w/Data $21.95
Now over 1 year successful field experience
“Special Offer” Buy (4) 8K 450ns. Kits $1 17.00

FLOPPY DISK DRIVES

1. VISTA V-80 MINIDISK
FOR TRS-80

★ 23% More Storage
Capacity- 40 Tracks

★ 40 track patch now avail.

★ Faster Drive - / , 0<5 M

Up to 8 Times Faster l 385 -°°

2 Drive Cable Add $29.95
4 Drive Cable Add $39.95

2. VISTA V-200 MINI-FLOPPY SYSTEM

★ 204 K Byte Capacity ★ w/CP M, Ba sic “E”

★ Double Density Drive

★ One Double Density ( V-200 \
Controller w/Case & P.S. \699.00/

Add to your EXIDY, HORIZON,
and other S-100 computers.

3. VISTA V-1000 FLOPPY DISK SYSTEM

★ (2) Shugart 8" Floppy Disk s

★ Controller Card, Cable, /T.

Case & P S.

★ CPM & Basic “E", \® 990 V

Instructions & Manual ^

4. MPI B51-5V4”, 40 tracks 279.00

5. Shugart SA400-5V4”, 35 tracks .... 295.00

6. Siemens/GSI FDD100-8 8” 375.00

7. Shugart 800/801 R 8" 495.00

8. PERSCI Model 277 Dual 1195.00

9. WANGO/SIEMENS 5V4’’ Drive . . . 290.00

EXPANDORAM MEMORY KITS

★ Bank Selectable ★ Uses 41 1 5 or 41 1 6

200 ns.

★ Write Protect ★ Power 8VDC, ±1 6VDC

★ Phantom ★ Lowest Cost/Bit

Expando 32 Kit (4 11 5) Expando 64 Kit (4 1 1 6)

8K $158.00 ' 16K $248.95

16K $199.00 32 K $369.00

24K $299.00 48K $469.00

32 K $349.00 64K $565.00

IMS STATIC RAM BOARDS

★ Memory Mapping ★ Low Power

★ Phantom ★ Assembled & tested

Recommended by Alphamicrosystems

250 ns. 450 ns.

8K Static $209.00 $189.00

16K Static $449.00 $399.00

32 K Static $799.00 $699.00

ANADEX PRINTER

Model DP-8000 compact, impact, parallel or
serial. Sprocket feed, 80 cols,
84 lines/min., bi-directional.
New only $895.00

FLOPPY DISKETTES

★ 5 V 4 ” Minidiskettes ★

$4.25 Each, 10/39.95
★ 8” Standard Floppy Disks
Soft Sector, Hard Sector
$4.50 Each, 10/41.95
*Add 4.95 for 1 0 Pack in Deluxe Disk Holder

Softsector, 10 Sector, 1 6 Sector

ssSfc*

9600 MPU Module w/6802 CPU $495 00

9601 1 6 Slot Mother Board 175.00

9602 Card Cage (1 9" Retma Rack Mount) . . . 75.00

9603 8 Slot Mother Board 100.00

9604 Switchmode System Power Supply .... 250 00

9610 Utility Prototyping Board 36.00

9616 Quad 8K Eprom Module ***

9620 1 6 Channel Parallet I/O Module — 295.00
9622 Serial/Parallel I/O Combo ***

9626 8K Static RAM Module 295.00

9627 16K static 450ns 495.00

9630 Card Extender 68.00

9640 Multiple Programmable Timer

(24 Timers) 395.00

9650 8 Channel Duplex Serial I/O 395.00

96103 32/32 I/O Module 275.00

96702 32 Point Reed Relay Module 350.00

6800 BARE BOARDS

9620-0 $45.00 9603-0 27.00

9626-0 45.00 9600 55.00

9650-0 45.00 96103 55.00

9601-0 50.00 96702 55.00

Also AMI EVK System in Stock

APPLE/EXIDY/EXPANDO
TRS 80 16K-UPGRADE KIT

★ 1 6K with Jumpers & Instructions

for either Level I or Level II $74.95

★ 16K for Apple II Upgrade $74.95

Special: TRS80 Schematic $ 4.95

Expansion Interface Schematic .... $ 4.95

TRS 80 TO S-1 00
PET TO S-100 ADAPTER

Allows Pet/TRS 80 to be interfaced to
popular S-100 Bus.

Pet to S-100 Kit $189.95

Assembled $269.95

TRS 80 to S-1 00 HUH 81 00 Kit ... . $275.00
Assembled $355.00

KEYBOARD ASCII ENCODED

One time purchase of
NEW Surplus key-
boards. From the Singer
Corporation. The
keyboard features 1 28
■JASCII characters in a 63
key format, MOS
encoder circuitry “N” key
rollover, lighted shift lock, control, escape and
repeat functions. Ltd Qty 63 KEY $59.95

UV “Eprom” Eraser

Model UVs-1 1 E $69.95

Holds 4 Eprom’s at a time
Backed by 45 years
experience.

Model S-52T. .. $265.00

Professional Industrial Model

TARBEL^LOPP^NTERFACE

★ Z80/8080 S 100 Compatible ★ Uses CPM

Assembled for Shugart SALE S259.95

Assembled Other Drives $269.95

Kit $179.95

Bare Board $36.95 (Doc. Add $10.00)

Note: For CPM Add $70.00. Documentation Add $20.00

Vista Double Density 5y«"Controller Assem $299.00

SD Versa Floppy Kit $159.95

SD Versa Floppy Assembled $189 95

Tarbel Cassette I/O Kit $11 5.00

>ale ★ 1771-01 Floppy Chip $27.95

BYTE USER 8K EPROM BOARD

★ Power on Jump ★ Reset Jump

Assembled & Tested $94.95

Byteuser Kit $64.95

Bare PC Board $21.95

Special Offer: Buy 4 kits only $59.95 each

MR-8 8K w/IK Ram $99.50

MR-16 16K w/IK Ram $99.50

EPM-1 4K 1702 $59.95

EPM > 22708or^n6Epron^^^^6^5

Z-80/Z-80A/8080 CPU BOARD

★ On board 2708 ★ 2708 included (450ns.)

★ Power on jump ★ completely socketed

Assembled and tested $185.00

Kit $129.95

Bare PC Board $ 34.95

★ For 4MHz Speed Add $15.00

8080A Kit $ 99.95

8080A Assembled $149.95

S-100 MOTHERBOARD SPECIAL

8 slot expandable w/9 conn.

reg $69.95 NOW $52.95

PROBLEM SOLVER SYSTEM USERS

We recently purchased all finished
goods, work in process and product de-
signs from P.S.S. Send for more details.

ACOUSTIC MODEM

NOVATION CAT 1 *'

0-300 Baud

Bell 103 J

Answer, Originate $ 1 98.00

ACOUSTIC COUPLER SPECIAL

AJ MODEL A30
SPECIAL PURCHASE
OF SURPLUS UNITS
AVAILABILITY LIMITED $29.95

DATA BOOKS • COMPUTER BOOKS

1979 1C Master 49.95 Intel MCS 80 Manual 7.95

NSC TTL Data 3.95 Intel MCS 40 Manual 4.96

NSC Linear 4.95 AMD 8080A Manual 5.96

NSC Linear App Notes II 3.95 AMD Schottky Databook . 4 95

NSC CMOS 3.95 AMI MOS/LSI Data . 3-95

NSC Memory 3.95 Gl MOS/LSI Data 4.95

Intel Databook 4 95 Harris Analog Databook 4.95

Intel MCS 85 Manual 7 50 T1 Linear Control Data. 3.95

SALS • OSBORNE BOOKS • SALE

Intro to Micros Vol. 0

Intro to Micros Vol. I

8080 A Programming.

6800 Programming ,

Z80 Programming 8"5Q

Vol. II Some Real Microprocessors w/8inder 30i«Q 27.50

Vol. Ill Some Real Support Devices w/Binder TtFOQ 18.50

Inlro to Micros Vol. Ill Togo. 18.50

SALE e DILITHIUM COMPUTER BOOKS e SALE
Understanding Computers . StSA. 7.95

8080 Microcomputer Experiments T5r9*. 1 1 .95

Beginning BASIC 8 95

Beginners Glossary 4 Guide 8-9*. 5.95

Peanut Butter 5 Jelly Guide to Computers TrSS. 6.95

8080 Machine Language Programming T-9*. 6.96

Home Computers Vol. I Hardware 6.96

tiume Computers VK. II Software T9.0S 1 1 .95

Starship Simulator . T36-. 6 95

P. O. BOX 17329 Irvine, California 92713

Send $1.00 for your
for the serious computer user.

MICROPROCESSORS STATIC RAM HEADQUARTERS SOCKETS

8 Pin W/W 32
4 Pm W/W 37

Z-80A
F 8 (38501
2650
CD I 802
8080A
8080A-4MHZ
SALE 8085
8008-1
2901
2901 A
TMS 9900JL
CP1600
6502
6S02A
IM610O

6800

680 2 P
8035
8755
8748

16 95

16 95
1895

17 95
995
19 95
19.99
1495
12 95
1995
4995
39 95
11 50

19.95
29 95

13.95
2495
1995

49.95
6995

SUPPORT DEVICES

AM9511Arrth Processor 519500

AM 951 1-1 300 ns 245.00

AM95 1 7 DMA Controller 7195

AM95 1 9 Universal Interrupt 24 95

3881 (Z80 PIO) 9.96

3881 4 14MHz) 14.95

3882 (Z-80 CTCl 9 95

3882-4 (4MHz) 14 95

3883SIO 29.95

3884 DMA 49 95

8205/74S 1 38 Decoder 2 95

82 1 2 8 bit I/O
82 1 4 Priority Int
8216 Bus Driver
8224 Clock Gen
8224-4 (4MHz)

8226 Bus Driver
8T26 Bus Dnver
8226 Sys. Control
6238 Sys Com
8251 Prog I/O
8253 Ini Timer
8255 Prog I/O
8257 Prog DMA
8259 Prog Int
8275 CRT Controller
8279 Prog Keyboard
6810-1 128*8 RAM

6820 PIA

6821 PI A
6828 Priority Int
6834- 1 512 * 8 Eprom
6850 ACIA
6852 Serial Adapter
6845'HD46505CRTCnnii

6862 Modulator
6871 A 1 OMHzOSC
6875

6880 Bus Driver
MC68488

1821 SCD IK RAM

1822 SCD 256* 4 RA

1824 CD 32 *8 RAM
1852 CD 8 bit I/O
1854 Uart 10.95

1856 CD I/O

1857 CD I/O
6520 PIA
6522 Mult
6530-002
6530-003
6530-004
6530-005

.19.95
2500
16 95
9 95
1095

8700 8 bit Binary

8701 10 bit Binary

8703 8 bit TS

9400 Volt to Freq Conv
0750 3-1/2 Digil BCD
1408L6 6 bit
laosLaa b,t
DACOIA/D

1 30
1 59
1 25

21 L02 450ns
2IL02 250ns
2102

2111 3 73

2112-1 2 95

2101-1 290

2114L-250ns. 12 95

21 14L-300ns 8 95

211 4L-450ns. 7 50

4044/4041 300ns. 9 95

4044/4041 450ns. 7 50

25-99
1 25
1 55

EMM4200A

EMM4402

EMM4804

510IC-E
Upd4 10 142001
AMDS U0/4 1
AM091 30/31

9.75
7 95
12.50
7 95
to 95
10 95
1295

7 95
10 25
1025

FSC 460 4641 6K CCD Only S18 9S Each

1101

1 95

1 75

P21 26/93426 145 ns i 7 95 7 35

6508 1 K « 1 CMOS 7 95 7 95

6518 IK * 1 CMOS 7 95 7 95

74S 1 89 64 bit Ram 3 95 325

8155 I/O w/Ram 2195
21 47 Lew Power 4K Static 14 95ea

16 Pm W/W 38
18 Pm W/W 60
2C Pm W/W 90
22 Pin W W 93
24 Pm W/W 85
28 Pm W W 1 16
40 Pm W/W l 49

8 Pm S/T 17
14 Pm S/T 20
16 Pm S/T 22
18 Pm S/T 31
20 Pm S/T 34
22 Pm S/T 35
24 Pm S/T 4 1
28 Pm S/T 49
40 Pm S/T 63

CHARGE COUPLED DEVICES

16K CCD - Firsl time ottered Fairchild 460 CCD
16K Memory (now you can e*penment with CCD
technology at a reasonable price 1 7 page Applica-
tion note supplied with each order Ouanlity limited)

$18.95 each (reg. 43.00)

250

4.50

2 50
295
9 75

3 95
239

5.95
625

6.95
1950

595

17.95

17.95
49 95

16.95

CRYSTALS

Microprocessor Timobases TV Game

Price Frequency Price

Frequency

1 UMHz
18432

2 0MH/
201MHr

2 097152MHz

2 4676MHz

3 579545MHz

4 0MHz

4 194304MHz

4 9 1 520MHz
50MHz

5 0668

5 7143MHz

5 95

6 0MHz
6 144
6 5536
10 0MHz
13 0MHz
1431818
18 0MHz
18 432MHz
20 0MHz
22 1184MHz
27 OMMz
36 0MHz
48 0MHz
100KC

DYNAMIC RAMS

416/4116 16K (16 Pin).. 9.95

Sol of 8 416 s 74.9/

4115 8K (16 Pin) 6.? j

4050 4K x 1 (18 Pin) 4.25

4060 4Kx 1 (22 Pm) 4.95

4096 4Kx 1 (16 Pin) 3 95

2104 4K x 1 (16 Pin) 4.75

4027 4K x 1 (16 Pin) 4 95

5261 1.95 1103 195

5262 1.95 40C8L 4.95

5270 4.95 6605 7.95

5260 4.95 6604. . 4 95

5290 12 45 6002. 1.50

PROMS

2706 995

2708-6 7.50

1702A 3 95

2732 99.00

2716-5V 44.95

2716-5V. 12V
2758 5V
5203 AO
5204 AO
6834-1
IM 5610

SALE 8223 32 x

82S1 1 5 512 x 8 (TS) 16.95

82S123 32 x 8 2 50

82S126 256x4 3 50

82S129 256 * 4 (TS) 3,50

82S130 512 x 4 (OC) 6.50

NSC DM7578 32 x 8 2.95

CHARACTER GEN

2513-001 (5V) Upper 9.50

2513-005 (5V) Lower . 10 .95

2513-ADM3(5V) Lower 14.95

MCM6571 10 75

MCM6571 A
MCM6S74
MCM6575

DISPLAYS/OPTO/LED'S

* 7 SEGMENT * CALC * CLOCKS *

DL 704 (CC), DL 707 (CA) .300" Red 99

FND 357 (CC) .357" Red 99

FND 500/503 (CC) .500' Red 99

FND 507/510 (CA) .500" Red 99

FND 800/803 (CC) .800* Red 1 .75

FND 807/810 (CA) 800" Red 1.75

XAN 3062 500' Green 115

HP5082-7731 (CA) .300" Red 99

9 Dgit Bubble Mini Calc. Display 99

9 Dgit Panapie* Display .400" 99

9 Dgit Fluorescent .300" 99

MAI 003 1 2V Auto Clock Module . 1 5.95

Bezel for MAI 003 w/Red Filter 4.95

8 95 MA1002A LED 1 2 hr Clock Module 10.95

8 95

7 50 * HEX DISPLAYS * ENCODED DISPLAYS *

9,25 HP 5082-7340 Red Hexidecimal 16.95

5 50 HP 5082-7300 Red Nymeric 14 95

1 5 50 TIL 306 Numeric w/Logic 8.95

15.50 TIL 308 Number w/Logic 8.95

1 5 50 TIL 309 Number w/Logic 8 95

TIL 31 1 Hexadecimal .... 1 2.95

MAN 2A .320" Red Alpha-Numenc 5.95

g 95 MAN 1 0A 270" Red Alpha-Numeric 8.95

TEXTOOL ZERO
INSERTION FORCE
SOCKETS

16 Pm S 5 50 24 Pin S7 50

40 Pn $10.25

CONNECTORS

DB25P (RS232) 3 25

DB25S Female 3 75

Hood 1 25

Set w/Hood. Sale
22/44 W/W S/T, KIM
43/86 W/W. S/T. MOT
50/100 S-100 Connector w/w 4 25

50/100 S-100 Connector s/I 325

S6 50
2 95
650

CTS DIPSWITCHES

CTS206-4 $1 75 CTS206-8 SI 95
CTS206-5 SI 75 CTS206-9 $1 95
CTS206-6 SI 75 CTS206-10 SI 95
CTS206-7 SI. 75

NAKED PC BOARD SALE

Z-80 CPU (llhaca) S34 95

8080A CPU 34 95

8K Static RAM (Logos! 2195

16K Static RAM (21 14) 29 95

32K Static RAM (2114) 4995

Floppy I/O (Tarbelf) 39 95

Cassette I/O (Tarbelt) 29 95

8K Eprom (2708) 21 95

1702 Eprom Board 300C

2708/27 1 8 Eprom (Ithaca) 34 95

2708/27 16 Eprom (WMC) 3000

Realtime Clock 34.95

ACP Proto Bd (3M Conn ) 27 95

Vector 8800 Proto 1995

Vector 8803 1 1 slot MB 29 95

ACP Extender w/Conn 15 95

Video Interface (SSM) 27 95

Parallel Interface (SSM) 27.95

i3SiotMotherBoard(WMC] 32 95
9 Slot Mother Boerd (WMC) 2995

8 Slot Mother (expandable) 34 95

WAVEFORM

GENERATORS

8036 Function Gen 3 95

MC4024 VCO 2 45

LM566 VCO 1 75

XR7206 Function Generator 5 25

FLOPPY DISK I/O

1771-01 8" & Minifloppy 27 95

uPd372 Nec Floppy 49 95

1781 Dual Floppy 29.95

1791 Dual Floppy 39.95

TV INTERFACES

Pixie-Verter

TV-1 Video Interface
Microverter
MAR Modulator

850

695

3500

3500

29.95
29.95

11 96
9 95

12 95
2 96

2.95

SPECIAL PURCHASE
(while supply lasts)

21L02-4 (450 ns) 100 @ 99$ ea.
21L02-2 (250 ns) 100 @ $1.15 ea.
TMS4060 NL 4K Dynamic RAMs
(pullouts) $1.95 ea.(prime);$3.75 ea.

1488 Line Receiver 100 @ 75c ea.

1489 Line Driver 100 @ 75c ea.

1489 House Marked 100 @ 50c ea.
1496 L Demodulator 25 @ 75c ea.
LM 3900 Quad Op Amp 3/$1.99
2716 5 Volts EPROM 3/$99.00

COMPUTER SPECIALS

1075
1450
14 50

UARTS/USRTS

TR1602B15V, 12V) 3 95

AY51013(5V. 12 V) 4.95

AYJ1014A/1612 (5-14V) 6 95

AY51015A/1863 <5V) 6 95

TMS 601 1 ISV 12V) 5 50

IM6402 795

IM6403 8.95

2350 USRT 9 95

167 IB Astros 24 95

SALE TR1472B 9.99

BAUD RATE GEN

MCI 4411 11.95

4702 14 95

WD1941 9 95

KEYBOARD ENCODERS

AY5-2376 13 75

AY5-3600 13 75

HD016S 9.95

74C922 9.95

74C923 9 95

A/D CONVERTERS

LIST

SALE

Apple II P1usw/16K

1195.

990.

IPSI 1620 Diable R0 3295.

2695.

PET 2001-16N

995.

895.

Anadex DP 8000

995.

895.

Exidy Sorcerer w/8K

895.

795.

Centronics Micro P-1

595.

395.

Compucolor II w/8K

1495.

1395.

Centronics Micro S-1

595.

525.

Cromemco Sys III

5990.

4990.

Soroc 10 1 20

995.

850.

Horizon lw/16K

1599.

1349.

Teletype Model 43

1349.

1150.

TEI PI 208 w/32K

HiPlot Plotter

1085.

899.

dual floppy & CRT

HiPlot Digitizer

795.

735.

(1 avail.)

4995

2995

Intertube II

895.

784.

Pascal Microengine

2995

2395

Proc. Tech. SOL-20

$1095.

13 50
22 OC
13.50
7 25
1395
395

* LED’* * OPTOISOLATERS *

LEDS Red. Yellow. Green 185 5/1 .00

MCT 2 Photo XSTR HFE 250, 30V 99

4N25 Photo XSTR HFE 250, 30V 1 29

4N33 Photo Darlington 1.76

FPT 1 1 0B Photo XSTR Flat Lense . SALE 4/ 1 .00

MONTHLY 1C SPECIALS

LF1 3506 JFET An log Multi 8 bit 8.95

ICM7208 Seven Decade Counter 1 7.95

ICM7207 Oscillator Controller 6.95

ICM7045 Precision Sto/Watch Timer 22 95

ICL7107 3V» Digit A/D (LED) 14 95

ICL821 1 Voltage Reference 1 .95

LM390 Battery OP. Audio Amp 3/1 .00

LM1850 Ground Fault 1C 3/1.00

LM 1 800 Phase Lock Loop FM Stereo 3/1 .00

LM1820 AM Radio 3/1.00

DS3625 Dual Mos Sense Amp 2.50

1408L8 4/1996 10147 ECL Ram .9.96

1488/1489 2/1.99 LF356HBiFet . .3/1.99

22 Pin S/T Socket 10/1.00 MCM14505 8 95

8223 Prom . . . . , 2.95 74S89 3/1.99

MK5014 Calc. 2/1.99 74107N 6/1.99

741 41 N 3/1.99 75462N 8/1.99

8T26/8T28 2 39 741N-14 10/1.99

06H3O 3.95 566CN 5/1.99

8281 50 556CN 3/1.99

TV CHIPS/SOUND

AY 36 500 1 6 Games B/W $4 95

AY385 1 5 Color Converter 2, 95

AY38603-1 Roadrace Game 8.95

AY38605-1 Warfare Game 9 50

AY38606-1 Wipeout Game 9 50

AY38607-1 Shooting Gallery 8 95

AY38910 Gimm. Cricket Sound

Generator 1 2.95

SN76477 Tl Sound Generator 395

MM5320/21 TV Synch Gen 9 95

MM5369 Prescaler 3.95

LM1689 RF Modulator 3 95

MM57 1000 NSC Color TV

Game 6.95

MM57104 Clock Gen 3.75

RF Modulator w/Audm 8 95

All Shipments FCM or UPS. Orders
under SI 0000 add 5% handling and
postage Orders over SI 00.00 add
2.5% handling & postage Master-
charge/ P ol A /American Express/
COD accepted w/25% deposit Cali-
fornia Residents add 6% tax Foreign
Orders add 8% handling. All parts
prime factory tested guaranteed
Add 35 cents lor Data.

Retail pricing may vary from Mail
Order Pricing. All pnemg subject to
change without notice

FOR INTERNATIONAL ORDERS: 1401 BORCHARD, SANTA ANA, CA 92705 PHONE 714-953-0604

Phone (714) 558-8813

14-953-0604 TWX: 910-595 1565

Retail Store Open Mon. Sat.
Located at 1310 "B” E. Edinger,
Santa Ana, CA 92705

v* Reader Service— see page 227

Microcomputing January 1980 207

7AV-S

CH\P S

15°/c

Off

\tt

MEMORY PRICES REDUCED !!!

Computer Products
S 0

sale «,

S D SYSTEMS

EXPANDORAM

EXPANDABLE TO 64K USING 4116 RAMS

Interfaces with most popular S-100 boards

Bank selectable; PHANTOM provision

Draws only 5 watts fully populated

Designed to work with Z-80, 8080, and 8085 systems

No wait states required

16K boundaries & protect via dip switches

Kits come with sockets for full 64K

Invisible refresh

MEM-16130K (16K KIT) $199.00

MEM-16130A (16K A&T) $249.00

MEM-32131K (32K KIT) $265.00

MEM-32131A (32K A&T) $315.00

MEM-48132K (48K KIT) $339.00

MEM-48132A (48K A&T) $389.00

MEM-64133K (64K KIT) $394.00

MEM-64133A (64K A&T) $444.00

S D SYSTEMS

PROM-100

VERSATILE EPROM PROGRAMMER

S-100 bus compatible (note: board height 7")

Dip switch selects 2708, 2716, 2732, 2758, or2516's
25 VDC programming pulse generated on board
Programming time only 100 seconds for 16K bits
Support-software listing provided in manual
Program and erasure verification
Software provides for reading of object file from
CP/M and programming into EPROM

MEM-99520K (KIT) $145.00

MEM-99520A (A&T) $215.00

S D SYSTEMS

EXPANDOPROM

S-100 bus compatible, uses 2708 or 2716 EPROMs
Dip switches allow selection of : each EPROM, 16K
or 32K boundary, wait states

MEM-32220K (KIT) $135.00

, MEM-32220A (A&T) $199.00

GET THE INSIDE TRACK

JADE DOUBLE-D

DOUBLE DENSITY DISK CONTROLLER

Read/write single or double density, 8" or 5y 4 ''drives
On board Z-80 insures reliable operation
CP/M compatible in either single or double density
Density is software selectable
Up to 4 single or double sided, single or double
density drives may be mixed on the same system
EIA level serial printer interface on board-up to 9600
baud (perfect for despooling operations)

All the hard work of disk access is done by the on
board Z-80A and 2K memory, leaving your host
CPU free for its normal duties
Uses IBM standard formats for proven reliability
THIS BOARD REALLY WORKS HUH

IOD-1200K (DOUBLE-D KIT) $285.00

IOD-1200A (DOUBLE-D A&T) $349.00

IOD-1200D (MANUAL ONLY) $15.00

S D SYSTEMS

VERSAFLOPPY II

DOUBLE DENSITY DISK CONTROLLER

Single or double density floppy disk controller

985600 bytes on 8” double sided diskettes

259840 bytes on double sided 5y 4 '' diskettes

S-100 bus (IEEE) standard compatible

IBM 3740 format in single density

8'' and 5y 4 '' drives controlled simultaneously

Operates with Z-80, 8080, and 8085 CPU's

Controls up to 4 drives

Vectored interrupt operation optional

IOD-1160K (KIT) $305.00

IOD-1169A (A&T) $399.00

S D SYSTEMS

VERSAFLOPPY

VERSATILE FLOPPY DISK CONTROLLER

IBM 3740 soft sectored format

S-100 Z-80 or 8080 compatible

Controls up to 4 single or double sided drives

Compatible with all popular disk drives

CP/M compatible

Listings for control software included

IOD-1150K (KIT) $139.00

IOD-1150A (A&T) $229.00

NEW 2 OR 4 MHz REV. C BOARD

THE JADE BIG Z

Z-80 CPU BOARD WITH SERIAL I/O PORT
2 or 4 MHz switchable, on-board 2708, 271 6, or 2732
EPROM useable in SHADOW mode (full 64K RAM)
Automatic MWRITE generation if no front panel
On-board USART for sync or async RS232

CPU-30201 K (KIT) $159.00

CPU-30201 A (A&T) $209.00

S D SYSTEMS

EXPANDORAM II

4 MHz RAM BOARD EXPANDABLE TO 256K

S-100 bus compatible, up to 4 MHz operation
Expandable memory from 16K to 256K
Dip switch selectable boundaries
Page-mode allows up to 8 boards on the same bus
Invisible refresh; PHANTOM output disable
Designed to operate in Z-80 based systems

MEM-16631 K (16K KIT) $275.00

MEM-16631 A (16K A&T) $325.00

MEM-32632K (32K KIT) $359.00

MEM-32632A (32K A&T) $410.00

MEM-48632K (48K KIT) $445.00

MEM-48632A (48K A&T) $495.00

MEM-64632K (64K KIT) $529.00

MEM-64632A (64K A&T) $579.00

S D SYSTEMS

VDB-8024

80 X 24 I/O MAPPED VIDEO BOARD

80 character by 24 line display, 7X10 dot matrix
Composite or seperate TTL video outputs
On-board keyboard interface with power
On-board Z-80 and 2K RAM
Blink, underline, reverse, protect, up/down scroll
Upper/lower case characters, 32 special characters
Optional 128 user-programmable characters

IOV-1020K (KIT) $295.00

IOV-1020A (A&T) $459.00

S D SYSTEMS

SBC-100/200

2 OR 4 MHz SINGLE BOARD COMPUTER

S-100 bus compatible Z-80
IK of on-board RAM

4 EPROM sockets accomodates 2708, 2716, or 2732
One parallel and one serial I/O port
4-channel counter timer chip (Z-80 CTC)

Software programmable serial baud rates

CPC-301 00K (2 MHz KIT) $215.00

CPC-301 00A (2 MHz A&T) $345.00

CPC-30200K (4 MHz KIT) $255.00

CPC-30200A (4 MHz A&T) $365.00 j

PRICES SLASHED FOR JANUARY !!!!

CALL TOLL-FREE AND SAVE

800-421-5809 CONTINENTAL U.S. 800-262-1710 INSIDE CALIFORNIA

S D SYSTEMS

Z-80 STARTER KIT

COMPLETE Z-80 MICROCOMPUTER

On-board keyboard, display, EPROM programmer,
and cassette interface
On-board S-1Q0 interface

Wire-wrap area and room for 2 S-100 connectors
Two 8-bit parallel I/O ports, 4-channel CTC, 5
programmable breakpoints

Examine and change memory, I/O ports, or register

CPS-30010K (KIT) $219.00

CPS-30010A (A&T) $365.00

CP/M 2.0

Digital Research has done it again! This new release of their
industry standard disk operating system is bound to be an
even bigger hit than the original version. All of the
fundamental file-size restrictions of release 1 have been
eliminated, while maintaining full compatibility with the
earlier versions. This new release can be field-configured by
the user for a single mini-disk up through a multiple drive
hard-disk system with 128 megabyte capacity. Field
configuration can be accomplished easily through use of the
Macro Library (DISKDEF) provided with CP/M 2.0.

A powerful operating system for only . . . $150.00

JADE'S NEW MOTHERBOARDS

THE ISO-BUS

WE'RE PROUD OF OUR MOTHER !

6-SLOT

BARE BOARD $24.95

KIT $49.95

ASSEMBLED & TESTED $59.95

12-SLOT

BARE BOARD $39.95

KIT $89.95

ASSEMBLED & TESTED $99.95

18-SLOT

BARE BOARD $59.95

KIT $129.95

ASSEMBLED & TESTED $149.95

SPECIAL PACKAGE PRICE

ROCKWELL AIM-65

JADE

MEMORY EXPANSION KITS

FOR

TRS-80 APPLE EXIDY

Everything you need to add 16K of memory to your
computer. Your kit comes neatly packaged with
easy to follow instructions. In just minutes your
computer is ready to tackle more advanced

$75.00

AVAILABLE IN FEBRUARY

NEW JADE P/S I/O

PARALLEL/SERIAL/INTERRUPT BOARD
Z-80 SIO/PIO, 2 CTCs, expands to 2 SIOs, 4 CTCs
4 serial ports (async, sync, bisync, SDLC/HDLC)

2 parallel ports with full handshake
Software baud rate generators, interval timers,
counters, and generates 32 vectored interrupts
Designed especially for MP/M multi-user multi-
tasking operating systems. For use with Z-80 only

IOI-1045B (BARE BOARD) $45.00

IOI-1045K (KIT) $169.95

IOI-1045A (A&T) $224.95

MICROPROCESSORS

F8 $16.95

Z80 (2MHz) $10.95

Z80A (4MHz) $14.95

CDP1802CD $24.95

6502 $11.95

6800 $12.50

6802 $20.00

8008-1 $15.95

8035 $24.00

8035-8 $24.00

8080-A $10.00

8085 $23.00

TMS9900TL $49.95

8080A SUPPORT DEVICES

8212 $5.00

8214 $4.65

8216 $2.95

8224 (2MHz) $4.30

8226 $2.75

8228 $6.40

8238 $6.40

8243 $8.00

8251 $7.50

8253 $20.00

8255 $6.40

8257 $19.95

8259 $19.95

8275 $69.95

8279 $17.70

USRT

S2350 $10.95

UARTS

AY5-1013A $5.25

AY5-1014A $8.25

TR1602B $5.25

TMS6011 $5.95

IM6403 $9.00

BAUD RATE GENERATORS
MC14411 $10.00

6800 PRODUCT

6821 P $5.25

6828P $12.00

6834P $16.95

6850P $4.80

6852P $7.50

6860P $9.25

6862P $12.00

6875L $7.30

6880P $2.50

CHARACTER GENERATORS

2513 Upper $7.95

2513 Lower $6.75

2513 Upper (5 volt) ... . 9.75

2513 Lower (5 volt) . $13.00

MCM6571 up scan . . $13.00

MCM6571 A down scan$10.95
PROMS

1702A $5.00

2708 $8.95

2716 $39.95

2716 (5v) $39.95

2758 (5v) $30.00

DYNAMIC RAMS
4116/416D 8 for $74.95

2104/4096 $4.75

2107B-4 $3.95

TMS4027/4096 $4.75

STATIC RAMS

21 L02 (450ns) $1.50

21 L02 (250ns) $1.75

2101-1 $2.95

2111- 1 $3.25

2112- 1 $2.95

21 14L (450ns) $5.75

2114L (300ns) $5.95

TMS4044 (450ns) $8.00

TMS4044 (300ns) $9.95

410D (200ns) $9.95

4200A (200ns) $9.95

Computer Products '

4901 W ROSECRANS, HAWTHORNE, CA 90250

213-679-3313

PLACE ORDERS TOLL FREE

800 - 262-1 710 800-421 -5809

INSIDE CALIFORNIA CONTINENTAL U.S.

WRITE FOR OUR FREE 1979 CATALOG
FOR CUSTOMER SERVICE OR TECHNICAL INQUIRIES
CALL 213-679-3317

TERMS OF SALE: Cash, checks, money orders, and credit
cards accepted Minimum order $10.00. California residents
add 6% sales tax Minimum shipping and handling charge
$2.50. Prices are for U S. and Canadian delivery only and are
subject to change without notice. For export prices and
information send for a JADE INTERNATIONAL CATALOG.

INTEGRAL DATA SYSTEMS

THE PAPER TIGER

132 COLUMN DOT MATRIX PRINTER

Up to 198 CPS
1.75 to 9.5 inch adjustable
tractor and friction feed.

Parallel and serial
interface.

98 character ASCII set.

80 to 132 columns.

6 or 8 lines per inch.

Eight software selectable
character sizes.

110, 300, 600, or 1200 baud.

PRM-33440 $995.00

PRM-33441(with graphics & 2K buffer). . $1195.00

DISKETTE SPECIAL

5.25" SOFT, 10, OR 16 SECTOR

10 for $29.95

8" SOFT SECTOR IBM COMPATIBLE

10 for $34.95

S-100 CONNECTOR SALE

HOLIDAY SPECIALS For Orders Received BEFORE December 31, 1979

HOLIDAY SPECIALS For Orders Received BEFORE December 31,1979

Zd

Radio Hut

201 LOCHWOOD MALL • DALLAS, TEXAS 75218

ORDER BY PHONE— 214-324-5509

PLEASE WRITE FOR CATALOG OR
WHILE IN DALLAS, VISIT OUR RETAIL
STORE AT 201 LOCHWOOD MALL,
DALLAS, TEXAS 75218
(GARLAND ROAD AT JUPITER).

ORDERING INFORMATION & TERMS: Orders under $1 5.00
add 75c handling. No C.O.D. We accept Visa, MasterCharge,
and American Express cards. Tex. Res. add 5% tax. Foreign
orders (except Canada) add 20% P&H. 90 Day Money Back
Guarantee on all items. Add 5% P&H, maximum $5.00.
ORDER BY PHONE — (214) 324-5509

The EXPANDORAM is available in versions
from 1 6K up to 64K, so for a minimum invest-
ment you can have a memory system that will
grow with your needs. This is a dynamic mem-
ory with the invisible on-board refresh, and IT
WORKS!

• Bank Selectable
1 Phantom

• Power 8VDC, +16VDC, 5 Watts

• Lowest Cost Per Bit

• Uses Major Brand 1 6K RAMS

• PC Board is doubled solder masked and has
silk-screened parts layout

I • Extensive documentation clearly written

SD EXPANDORAM

n>

• Complete kit includes all Sockets for 64K

• Memory access time: 375ns, Cycle time:!
500ns.

• No wait states required

25! • 16K boundaries and Protection, via Dip|

Switches

• Designed to work with Z-80, 8080, 80851

CP U ? s 1

EXPANDORAM 64K Kit (16K Ram)

WITHOUT MEMORY $139.00

16K 209.00

32K 275.00

48K . 340.00

64K 405.00

SD’S PROM 100 PROM Programmer Board

The PROM-1 00 Programmer is a development tool for
S-100 Bus computer systems. The Zero Insertion
Force Programming Socket extends above the card
cage height for easy access to PROM devices. Soft-
ware verifies PROM erasure, verifies program loading
and provides for reading of object file from Disk or
PROM and programming into PROM/EPROM. Fea-
tures include: On-board generated 25vdc Program
ming pulse, TTL compatible, maximum programming
time for 16,389 bits is 100 seconds. Programs: 2708,
Intel 2758, 2716, 2732 and Tl 2516. DIP Selectable
EPROM type.

PROM-1 00 Board Kit $1 49.95

SD’S MPB-100
Z80 CPU
BOARD KIT

The MPB-100 provides,
a Z80 microprocessor
based CPU for S-100 Bus systems. Front panel us-
age is optional, making the MPB-100 suitable for
upgrading existing systems to Z80 level. A PROM
socket is provided on-board which makes the MPB-
1 00 adaptable to process control applications. Fea-
tures include: Power-on Jump to 4K boundaries, 2
Megahertz or 4 Megahertz operation, optional wait
states, on-board PROM socket.

MPB-100 KIT $199.00

SD’S VERSAFLOPPY II

• IBM 3740 Compatible Soft Sectored Format for Single Den-
sity Drives • Operates with Single and Dual Sided Drives,
Single or Double Density Drives and 5” & 8" Drives — in any
combination of four simultaneously • Drive Select and Side
Select Circuitry • S-100 Bus Compatible • Vectored Interrupt ^
Operation Optional • Phase Locked Loop Data Recovery Cir-
cuit • Operates with 280 CPU's • Uses FD1 791-1 Controller
Chip • Ther Versafloppy II incorporates all the possible fea-
tures of a flexible disk drive controller into one board. Capable
of handling four drives simultaneously, combinations of any
vanety are possible, such as 5” single sided, 8" dual density
dual sided, 5” dual density single sided. Most popular drives
are controlled directly with the Versafloppy II. The operating
system for the Versafloppy II is the extremely powerful SDOS
available for SD Systems. Diagnostic and control software |
available to complete your disk system.

$290 KIT, $385.00 ASSEMBLED & TESTED

SD’S VDB-8024
VIDEO DISPLAY
BOARD

The VDB-8024 features
its own on-board Z80
microprocessor. This gives the capability of using soft-
ware (included in ROM) to control functions and en-
hancements without interference with the computer’s
CPU. Included in the special features: 80 characters
by 24 lines display, keyboard power and interface,
composite and separate video output, 2K on-board
RAM, a total of 256 available characters, full cursor
control, forward and reverse scrolling, underlining,
field reverse, field protect enhancements, program-
mable characters. VDB-8024 KIT $289.00

SD’S

“VERSAFLOPPY I”

KIT

FEATURES: IBM 3740 soft sectored

compatible, S-100 BNS Compatible for Z-80
or 8080. Controls up to 4 drives (single or
double sided). Directly controls the following
drives: Sugart SA400/450 Mini Floppy • Shu-
gart SA800/850 Standard Floppy • PERSCI
70 and 277 • MFE 700/750 • CDC 9404/9406
$135.00

SD’S SBC-100
SINGLE BOARD
COMPUTER

The SBC-100 provides a
complete micro-computer
on a single board! The Z80 microprocessor is used as the heart
of the SBC-100. The SBC-100 meets all the requirements of a
Z80 CPU board with the added features of I/O ports, counter/
.timer channels, on board RAM, provisions for PROM/ROM
and a software programmable baud rate generator. S-100 Bus
compatible, the SBC-100 features are: 8K bytes of’available
PROM, 1024 bytes on-board RAM, Serial I/O with both syn-
chronous and asynchronous operation, Parallel I/O ports. [
Operational Vectored Interrupts, and Four Counter/Timer 1
Channels. SD Monitor available for RS-232 and Video Ter- ]
mmals. Disk based system software also available.

SBC-100 KIT $209.00

TARBELL FLOPPY DISK INTERFACE

Compatible with Z80 & 8080. S-100 Bus. Uses
CPM operating system. Plugs directly into your
IMSAI or ALTAI R • Fastest transfer rate

KIT $1 90.00 Assembled & Tested $260.00

TARBELL CASSETTE INTERFACE

Plugs directly into your IMSAI or ALTAI R •
Fastest transfer rate • Extremely reliable •
Phase encoded • 4 extra status & control lines

KIT $99.95

COMPUTER CORNER

CPU’S

Z80 $10.99

RELATED CHIPS

21 14 (300ns) v $5.99

Z80PIO $9.95

2708 $7.99

4115 8/S34.95

4116 8/$80.00

DISC CONTROLLER

1771 $29.95

1791 $37.95

1C SOCKETS

SOLDER TIN
PIN

8 .12

14 .15

24 .32

28 .39

LOW PROFILE
PIN

16 .17

18 .24

40 .54

20 .26

Z80 STARTER KIT

Kit: $21 9.95 Assembled & Tested $369.95

SD System's Z80 Starter Kit enables the novice to build a
complete microcomputer on a single board. Featuring the
powerful Z80 microproces-
sor, the Z80 Starter Kit fea-
tures • Keyboard and Dis-
play • Audio Interface •

PROM Programmer • Ex-
pansion and Wire Wrap
Area • On Board RAM • 4
Channel Gounter/Timer •

Z-BUG Monitor in PROM •

I/O Ports.

DIP

SWITCHES

3 Pos.

$1.10

4 Pos.

$1.12

5 Pos.

$1.16

6 Pos.

$1.20

7 Pos.

$1.22

8 Pos.

$1.26

9 Pos.

$1.36

10 Pos.

$1.30

LEDS AND READOUT

Jumbo Red LED s 8/1.00
Jumbo Green LED's 4/.95
Jumbo Yellow LED’s 4/.95
Jumbo Amber LED’s 4/.95
MV Red 10/1.00

FND 70CC .50

DL 707 .95

DL 747CA .65

DL728CC 1.19

FND800CC 1.50

Red Filter 4 Bezel 2.50
Green Filter 4" Bezel 2.50
Amber Filter 4 Bezel 2.50
4N25 1.60

4N26 1.25

4N27 1.10

4N28 .95

4N31 1.20

S-100 CONNECTORS
High-Quality Gold Pins
$2.99 EACH

FLOPPY DISK SPECIAL

5.25" SOFT, 10 OR 16 SECTOR

10 FOR $29.95

8" SOFT SECTORED IBM COMPATIBLE

10 FOR $34.95

• S-100 Bus Compatible

• Up to 4Mhz Operation

• Expandable Memory from 16K to 256K
* DIP Switch Selectable Boundaries

Uses 1 6K (41 1 6) or 64K (4164) Memory
Devices

| • Page Mode Operation Allows up to 8 Memory
Boards on Bus
► Operates with Z80 CPU’s
| • Phantom Output Disable

Invisible Refresh (Synchronized with Wait
States)

SD’S EXPANDORAM II
The Randem Access Memory

SD Systems’ ExpandoRAM II is a dynamic RAMI
board with capacities from 16K bytes (4116) tol
256K bytes (4164). It operates on the industryl
S-100 Bus. The design allows 8 boards to op-r
erate from the same 5-100 Bus. The Expando-|
RAM II is compatible with most S-100 CPU’s|
based on the Z80 microprocessor.

EXPANDORAM II KIT

W/O $195.00

16K 285.00

32K 375.00

48K .465.00

64K .555.00

6Z6 V ‘ IX Jaqiuaoaa 3HOd3S paAjaoay sjapjQ JQj SI VI03dS AVQITOH

HOLIDAY SPECIALS For Orders Received BEFORE December 31, 1979

Power Supplies! Power Supplies! Power Supplies! SOLID STATE!! (5)

We go* 'em! Take yo u r pick

fhpsp unit*: are ideal f nr mirrn pnmnntpre Thev hav/p hppn rpmnupH frnm pnuinmpnt

e e e

These units are ideal for micro computers. They have been removed from equipment, checked out
and guaranteed.

1— 5 volts @ 8 amps + 12 volts @ 2 amps + 6 volts @ 75 MA. Power supply has a 3-wire line cord and fused. Dimensions:

10V2” x 5 Vi” x 4 Vi”. Shipping weight: 16 lbs 37.50 ea. 2/70.00

2— Model 818, 5 volts at 15 amps + 12 volts at 4 amps-12 volts at 2 amps, (with line cord) 35.00 ea. 2/65.00

3— + 5 volts at 5 amps ±12 volts at 500 ma. + 6 volts at 25 ma. (line cord included) 32.95 ea. 2/60.00

4 — Elexon, multi output. Input: 120/240 AC, +10%, 47-63 hz; output: 1)1 2V, 1.5A, DC, OVP; 2) 12V, 1.5A, D.C.,

OVP. New, in box with operating instructions . . 31.50

5— Power Design, Model 1210, constant voltage, DC. P.S. input: 105-125. A.C., 55 to 440 hz. Output: 1-12 volts,

0-10 amps, DC. continuously adjustable output voltage and current limiting 139.00

COMPUTER GRADE CAPACITORS . . .

18.000 mfd 10 VDC
4,400 mfd 20 VDC

46.000 mfd 20 VDC
3,000 mfd 25 VDC

1.25

1.00

2.50

1.00

11.000 mfd 25 VDC

35.000 mfd 35 VDC

10.000 mfd 50 VDC

22.000 mfd 60 VDC

1.50

3.50

2.50
3.75

4.000 mfd 75 VDC

1.000 mfd 100 VDC
6,800 mfd 100 VDC
4,700 mfd 150 VDC

1.75
1.00
3.50

3.75

WIRE WRAP BOARDS

These boards have been removed from equipment. They're prewired, and very
easy to unwrap for setting up your own boards. Contains mostly 14-pin 1C
sockets with individual connections. Each board has VCC and ground planes.

Smaller board measures 6J4"x6" and has 40 to 50 sockets. Reduced Price. . . $7.50 ea. 2/$14.00
Larger board measures 13)4"x6" and has 75 to 100 sockets. Reduced Price ... $1 2.50 ea. 2/$23.00

DIABLO System Disc Drive

SERIES 40, MODEL 43

100 tracks per inch, total capacity of 50 mega-
bits, w/Model 429 power supply, sector counter,

24 sectors, 1 fixed disc, 1 removable disc, aver
age access time 38 ms, PPM:2B00, dimensions:

10 5/16" high, fits in standard rack, equipped
with full extension slides, excellent used
condition. Shipped freight collect.

HEWLETT-PACKARD MODEL 175A

OSCILLOSCOPES

$2495

THESE SCOPES HAVE A 50 MHZ BANDWIDTH AND
HAVE 2 PLUG INS, A 1781B DELAY GENERATOR
AND A MODEL 1755A DUAL TRACE VERTICAL
AMPLIFIER. DIMENSIONS: 13” x 17” x 25”,
WEIGHT 71 LBS, SHIPPED FREIGHT COLLECT. 5”
CRT. USED. CHECKED OUT AND OPERATING.

$ 339

TRANSFORMERS

ISOLATION STEP-DOWN TYPE

Primary: 230/1 15V, 50/60

CPS, Secondary: 115 volts 05

output 250 VA. EACH

ROTRON
WHISPER FANS

Unused, Model Rotron
MU 3A1, 230V, AC, 14
watts, 50/60 hz, guar-
anteed, 4%"x4%"x1%"

$8.95

Clock Crystal Oscillators -TTL, Vectron,
type CO-231T. Crystal freq. 4.9152 mhz. In-
put voltage 5 VDC ± . Output: Drives 10 TTL
Loads Logic “0”: 0.4V max., sink 16ma.
Logic “1” 2.4V min source 2 ma. (above 50
mhz drives 2 Schottky TTL loads). Tuning
adjust, with nominal range of ±30 ppm
below 25 mhz and 15 ppm above 25 mhz.
R.F.E. 1%"x1%"x%" $13.95

SG-132 SWEEP SIGNAL GENERATOR

FREQ: 15 TO 400 MHZ, VHF-UHF

Output: AM 8t FMi CW. FM deviation: + 1% to + 20% at any frequency.
Crystal markers every 200Khz, Imhz, 5mhz or + 10B. Frequency accur-
acy +1%. Built-in oscilloscope for observing Q AQ

waveforms.

TRENDLINE PHONES

Manufactured by I.T.T.

These units have rotary dials. Colors are: white, black, red,

and green. They are packaged and have 6-foot cord and

installation instructions. Used, C A

but in good operating condition. 04*dU WALL TYPE

Minimum order $25.00. Items offered subject to prior sale. FOB, Brockton, Mass. Money order or check w/order. Shipments
and handling add 5%. Shipments by parcel post or UPS. No CODs. Mass, residents add 5% sales tax.

WALLEN

ELECTRONICS CO. INC. Tel: (617) 588-6440-6441

108 SAWTELL AVE., BROCKTON, MA. 02402

ELECTRONIC COMPONENTS
TEST EQUIPMENT
CONNECTORS- WIRE

v * Reader Service — see page 227

Microcomputing January 1980 211

••••>

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16K EPROM CARD-S 100 BUSS

OUR

BEST

SELLING

KIT!

USES 2708 s!

Thousands of personal and business systems around
the world use this board with complete satisfaction.
Puts 16K of software on line at ALL TIMES! Kit features
a top quality soldermasked and silk-screened PC board
and first run parts and sockets. All parts (except 2708’s)
are included. Any number of EPROM locations may be
disabled to avoid any memory conflicts. Fully buffered
and has WAIT STATE capabilities.

OUR 450NS 2708’S
ARE $8.95 EA. WITH
PURCHASE OF KIT

ASSEMBLED
AND FULLY TESTED
ADD $25

8 K LOW POWER RAM KIT-S 100 BUSS

SALE

pHTTWiTifiiK? x'iian

w-ipl*

--Muy- »,■ - -‘u ( *■•:■?£ ' V" wgvr

•y tv f »■ y/VfV'V rrm

rrr* r * r*~~ \ —iT v '~M - 4 • 'osrw m

$ 1 1 9 5 k?t

(450 NS RAMS!)

Thousands of computer systems rely on this rugged, work
horse, RAM board. Designed for error-free, NO HASSLE,
systems use.

KIT FEATURES:

1. Doubled sided PC Board with solder
mask and silk screen layout. Gold
plated contact fingers.

2. All sockets included.

3. Fully buffered on all address and data
lines.

4. Phantom is jumper selectable to pin
67.

5. FOUR 7805 regulators are provided

yv on card.

Blank PC Board w/Documentation

$29.95

Low Profile Socket Set. .13. 50
Support IC’s (TTL & Regulators)

$9.75

Bypass CAP’S (Disc & Tantalums)

$4.50

ASSEMBLED AND FULLY
BURNED IN ADD $30

!•**.•

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§••**.

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§••**•

M*«*.

M**.

»••*..

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I

•••-

16K STATIC RAM KIT-S 100 BUSS

PRICE CUT!

$ 279

KIT

§•••-

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!•**.<

••••*

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!••*..

M**..

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FULLY
STATIC, AT
DYNAMIC PRICES

WHY THE 2114 RAM CHIP?

We feel the 21 1 4 will be the next industry standard
RAM chip (like the 2102 was). This means price,
availability, and quality will all be good! Next, the
21 14 is FULLY STATIC! We feel this is the ONLY
way to go on the S-100 Buss! We’ve all heard the
HORROR stories about some Dynamic Ram
Boards having trouble with DMA and FLOPPY
DISC DRIVES. Who needs these kinds of
problems? And finally, even among other 4K
Static RAM’s the 2114 stands out! Not all 4K static
Rams are created equal! Some of the other 4K’s
have clocked chip enable lines and various timing
windows just as critical as Dynamic RAM’s. Some
of our competitor’s 16K boards use these ''tricky"
devices. But not us! The 21 14 is the ONLY logical
choice for a trouble-free, straightforward design.

KIT FEATURES:

1. Addressable as four separate 4K Blocks.

2 ON BOARD BANK SELECT circuitry.
(Cromemco Standard!). Allows up to 512K on
line!

3. Uses 2114 (450NS) 4K Static Rams.

4 ON BOARD SELECTABLE WAIT STATES.

5. Double sided PC Board, with solder mask and
silk screened layout. Gold plated contact fingers

6. All address and data lines fully buffered.

7. Kit includes ALL parts and sockets.

8. PHANTOM is jumpered to PIN 67.

9 LOW POWER: under 2 amps TYPICAL from the
*8 Volt Buss

10. Blank PC Board can be populated as any
multiple of 4K.

BLANK PC BOARD W/DATA— $33
LOW PROFILE SOCKET SET-$12 ASSEMBLED & TESTED-
SUPPORT IC S & CAPS— $19.95

ADD $30

16K STATIC RAM SS-50 BUSS

PRICE CUT!

$ 275

KIT

FULLY STATIC
AT DYNAMIC PRICES

KIT FEATURES:

FOR SWTPC
6800 BUSS!

ASSEMBLED AND
TESTED - $30

_ _

1. Addressable on 16K Boundaries

2. Uses 2114 Static Ram

3. Runs at Full Speed

4. Double sided PC Board. Solder
mask and silk screened layout.
Gold fingers.

5. All Parts and Sockets included

6. Low Power: Under 2 Amps

Typical

COMPLETE SOCKET SET— $12

•••##<

BLANK PC BOARD— $33

SUPPORT IC’S AND CAPS— $19.95

S-100 Z80 CPU CARD

ASSEMBLED AND TESTED! READY TO USE! Over 3 years of
design efforts were required to produce aTRUE S-100 Z80CPU

at a genuinely bargain price! a iu|H7l $1 *;Q95
FEATURES- H win*.. 133

★ 2 or 4 MHZ Operation.

★ Generates MWRITE, so no front panel required.

★ Jump on reset capability

★ 8080 Signals emulated for S-100 compatability.

★ Top Quality PCB, Silk Screened, Solder Masked, Gold Plated Contact
Fingers.

Perfect For
OEM’s

LOW POWER - 250NS

2114 RAM SALE!

4K STATIC RAM’S. MAJOR BRAND, NEW PARTS.

These are the most sought after 2114’s, LOW POWER and

25ons FAST. $750 ea or 8 For s 55

SPECIAL SALE: (We reserve the right to limit quantities.)

PROC. TECH. QUITS THE MICROPROCESSOR BUSINESS!
FACTORY CLOSE OUT - SPECIAL PURCHASE!
#16KRA

16K S-100 Dynamic Ram Board - $149. 95

ORIGINALLY PRICED AT $429 each!

We purchased the remaining inventory of PT’s popular
16K Ram Board when they recently closed their plant.
Don’t miss the boat! These are brand new, fully tested,
ASSEMBLED and ready to go. All are sold with our
standard 90 day limited warranty!!

72 Page Full Manual, Included Free!

• •••<

NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE SUPPLIERS OF CPM SOFTWARE.

Digital Research: Computers

^ (OF TEXAS) r

P.O. Box 401565 • GARLAND, TEXAS 75040 • (214) 494-1505

TERMS: Add $1.00 postage, we pay balance. Orders under $15 add 75C
handling. No C O D. We accept Visa, MasterCharge. and American Express
cards. Tex. Res. add 5% Tax. Foreign orders except Canada add 20% P & H.90
Day Money Back Guarantee on all items.

10-DAY FREE TRIAL

Send for our
FREE Catalog

8K-Keyboard N $795

16K-Keyboard B $995

16K-Keyboard N $995

32K-Keyboard C 1,295

32K-Keyboard B $1,295

32K- Keyboard N $1,295

C— calculator keyboard (only version with tape deck)

B — large keyboard (graphics not on keys)

N — large keyboard with graphics symbols

$100 FREE ACCESSORIES
WITH 16K or 32K PET

When you buy a 16K or 32K PET, apply $100 toward PET
accessories. FREE. Just indicate on your order that you have
reduced the cost of your accessories by $100.

Terminal Package with 8K PETs

See Special Below

PET ACCESSORIES

Commodore Dual Floppy Disk Drive $1,100

Computhink 800K Disk Drive $1,295

Commodore Printer (tractor feed) $849

Commodore Printer (friction feed) $995.00

Second Cassette- from Commodore S95 00

Commodore PET Service Kit S30 00

Beeper-Tells when tape is loaded $24 95

Petunia- Play music from PET $29 95

Video Buffer- Attach another CRT S29 95

Combo- Petunia and Video Buffer S49 95

New Serial Printer Interface for PET $79 95

KIM 1 (A Single Board Computer
from Commodore) $179 00

Hazeltine 14001

Immediate Delivery —

\ 2-Year Factory Warranty

SALE

$649

Hazeltine 1410 — $835
Hazeltine 1500 — $1069

Hazeltine 1510 — $1195
Hazeltine 1520 — $1499

COMMODORE^^
DISK DRIVES

Reg. $1,295 Sale $1,100

$195

The r

apple II

1 p/us

(200 FREE ACCESSORIES

i new Apple II with Applesoft BASIC built-in! Elimi-
nates the need for a $200 Firmware Card and includes I
new Autostart ROM for easy operation. This combined I
with the FREE accessories from NCE could save you up I
to $400 on a 48K Apple II system!

J 1 6K Apple II Plus — $1195 (take $100 in free accessories)
32K Apple II Plus — $1 345 (take $1 50 in free accessories)
48K Apple II Plus — $1495 (take $200 in free accessories)

Apple II Accessories

General Business $625

PASCAL $495

Integer BASIC ROM Card $200

VISI-Calc $99

Centronics Printer Interface $225

Disk and Controller $595

Parallel Printer Card $180

Communications Card $225

Hi-Speed Serial Card $195

Firmware Card $ 200 .

IN STOCK NOW!

EVERY ITEM IN THIS ADVERTISEMENT IS IN STOCK
AND READY TO SHIP, EXCEPT WHERE NOTED.

PAPER TIGER 440SPE

The Graphics Printer
for Apple II

Now you can print illustrations, block letters, charts,
graphs, and more — all under software control And
with the expanded buffer, the Paper Tiger can hold the
text from an entire 24-line-by-80-column CRT screen

$1194.00

PET OWNERS . . .

REMOTE

TERMINAL

for

only $69

A self-contained
module and program
cassette enables your
PET to function as a
300 baud terminal.
Supports Upper/Lower
case, Rubout, Escape
& all control functions
Output is TTL.

from Heath Data Systems

The All-In-One Computer

Dual Z-80 Processors • Built-in 102K Floppy Disk • 16K
to 48K RAM • 25 x 80 Character Display • Upper/Lower
Case and Line Graphics • 80 Character Keyboard with
Keypad • 8 User-definable Keys • Two BASIC's and
Auto-Scribe Word Processing available • Can support
CP/M

Heath s third generation of computers is a compact,
hi-style desktop unit which includes a complete termi-
nal, a computer and a disk All-In-One! System includes
Bootstrap in ROM. other programs available separately.
HDOS operating system includes Heath's BASIC, an as-
sembler and text editor along with important disk
utilities. Microsoft language requires HDOS.

Lear Siegler’s ADM-3A

Back Again at Our Lowest Price Ever

The ADM-3A is industry’s favorite dumb terminal for
some very smart reasons

• 12 in diagonal screen

• Full or half duplex operation at 11 selectable data
rates

• 1920 easy-to-read characters in 24 rows of 80 letters

• Typewriter-style keyboard

• RS-232 C interface extension port

• Direct cursor addressing

Our Low Sale Price $795

ZENITH COLOR
VIDEO MONITOR I

Zenith’s first color video display
designed specifically for computers.

This 13-inch monitor is Zenith's first color video display I
designed specifically for computers Features include
automatic color level, color processing and degaussing
circuits.

Zenith Color Monitor $499.00

Just Released

CompumaiTs New
Fall/Winter 1979 Catalog.

We've just published our catalog and its packed with
new products and money saving specials. Our
illustrated 32-page book features microcomputers and
microcomputer systems from Apple. Commodore PET,
Heath and Exidy Sorcerer. Also covered are the
Commodore's KIM and Rockwell's AIM A broad
selection of terminals, books, software and peripherals
are presented in detail. The text is thorough and
provides a wealth of technical information. To get your
FREE copy write to our address below Please include
the dept, number to speed handling.

WH89 with 16K RAM $2,295

WH89 with 32K RAM $2,445

WH89 with 48K RAM $2,595

WH1 7 Second Disk Drive $550

Dual-port Serial Interface $85

HDOS Operating System $100

Microsoft BASIC $100

Word Processing $395

CENTRONICS 779-2 PRINTER

TRACTOR FEED

• Parallel interface

• Continuous variable
printing density 80-132
characters per line

• 5x7 dot matrix

SALE PRICE $1095

' Form thickness control |
• Horizontal and vertical
form positioning
Used with controller
(Apple general
business software)

SANYO MONITOR
$169 $279

9-inch 15-inch 4 im

CompuMart

DEPT. BC10

SINCE
1971 N7

270 THIRD ST.. CAMBRIDGE. MA 02142

To Order: 1 (800)343-5504
In M. 8S 1(617)491-2700

| 1 ^ ^ ^ Member

Computer Dealers

l J ^ ^ ^ Association

IMPORTANT ORDERING INFORMATION
All orders must include 4% shipping and handling. Mass, residents add 5% sales tax; Mich,
residents 4%, for sales tax.

Phones open from 8:30 a.m. to 5:30 p.m. EST Mon.-Frl. • P.O.’s accepted from D&B rated
companies — shipment contingent upon receipt of signed purchase order • Sorry no C.O.D.s •

All prices are subject to change without notice • Most Items in stock for Immediate shipment —
call for delivery quotation • In «ie Ann Arbor area? Our retail store is open 11:00 a.m. to 7:00 p.m.
Tues.-Frl., 10:00 a.m. to 5:00 pm. Saturdays (dosed Sun. and Mon.)

If not satisfied, return your purchase with-in 10 days for full
refund of purchase price!

Header Service— see page 227

Microcomputing January 1980 213

[t«* Continuity Tester and Flashlight

Convenient versatile tool for quickly
checking continuity of dead circuits,
switches, appliances, cords, fuses,
motors, control equipment, coils
and panel boards. Also tests cir-
cuits for low-resistance shorts and
helps identify wires in multi-wire
cables. Dozens of other uses. Plus
the added convenience of a handy,
durable flashlight. Uses two AA size
penlight batteries (not furnished).
Insulated clip prevents accidental
shorting to case. Alligator clip has
48” lead with plug.

*7.95

RT300

Custom Cables & Jumpers

DB 25 Series Cables

Part No.

Cable Length

Connectors

Price

DB25P-4-P

4 Ft.

2-DP25P

$15.95 ea.

DB25P-4-S

4 Ft.

1 -DP25P/1 -25S

$16.95 ea

DB25S-4-S

4 ft.

2-DP25S

$17.95 ea.

Dip Jumpers

DJ14-1

1 ft.

1 14 Pin

$1.59 ea.

DJ16-1

1 ft.

1-16 Pin

1.79 ea.

DJ24-1

i ft.

1-24 Pin

2.79 ea.

DJ14-1 -14

1 ft.

2-14 Pin

2.79 ea.

DJ16-1-16

1 ft.

2-16 Pin

3.19 ea.

DJ24-1-24

1 ft.

2-24 Pin

4.95 ea.

Forj^ustcmKMIe^Ji^

* ,,A

t J8..IL

25 PIN-D SUBMI
nnuucm

NIATURE

pfiDC

CONNECl

I0R5

(Meets RS232)

PART NO.

DB25P
0B25S
DB51 226-1
DB25P 831
DB25S-831

DESCRIPTION

PLUG (as pictured)

SOCKET

CABLE COVER for DB25P or DB25S. .
PLUG - Right Angle - P.C. Mount . . .
SOCKET - Right Angle - P.C. Mount .

PRICE

. $2.95
. 3.50
. 1.75
. 4.95
. 5.25

Printed
Circuit
Connectors

PART NO.

.156 Spacing-Tin-Double Read-Out
Bifurcated Contacts
Fits .054 to .070 P.C. Boards

DESCRIPTION

PRICE

1 5/30 SE

1 5/30 Contacts - solder eyelet

$1.95

18/36 SE

18/36 Contacts - solder eyelet

2.49

22/44 SE

22/44 Contacts - solder eyelet

2.95

22/44 WW

22/44 Contacts - wire wrap

3.95

50/1 00 WW

50/100 Contacts - wire wrap (R681-1).
(.125 Spacing)

6.95

Jumbo 6-Digit Clock Kit

* Four ,630”ht. and two .300”ht.
common anode displays

* Uses MMS314 clock chip

* Switches for hours, minutes and hold functions

* Hours easily viewable to 30 feet

* Simulated walnut case

* 115 VAC operation

* 12 or 24 hour operation

* includes all components, case and wall transformer

* Size: 6% x 3V» x l¥i

JE747 $29.95

• Bright .300 ht. comm, cath-
ode display

• Uses MM5314 clock chip

• Switches for hours, minutes
and hold modes

• Hrs. easily viewable to 20 ft.

• Simulated walnut case

• 115 VAC operation

• 12 or 24 hr. operation

• Incl. alt components, case fit
wall transformer

• Size: 6%” x 3-1/8” x 1%"

JE701

6-Digit Clock Kit $19.95

Regulated Power Supply

Uses LM309K. Heat sink ,

provided. PC board con- ' ^ °
struction. Provides a solid
1 amp @ 5 volts. Can supply up
to ±5V, ±9V and ±12V with
JE205 Adapter. Includes compo-
nents, hardware and instructions.

Size: 3y a ” x 5” x 2"H

JE200 $14.95

ADAPTER BOARD
-Adapts to JE200 —
±5V, ±9V and ±12V

DC/DC converter with +5V input. Toriodal hi-
speed switching XMFR. Short circuit protection.
PC board construction. Piggy back to JE 200
board. Size: 3Vi" x 2” x 9/1 6”H

V^JE205

$12.95

MICROPROCESSOR COMPONENTS

8080A

8212

8214

8216

8224

8226

8228

8238

8251

8253

8255

8257

8259

MC6800

MC6802CP

MC6810API

MC6821

MC6828

MC6B30L8

MC6850

MC6852

MC6860

MC6862

MC6880A

-808QA/808QA SUPPORT DEVICES—

CPU

8-Bit Input/Output
Priority Interrupt Control
Bi-Directional Bus Driver
Clock Generator/Driver
Bus Oriver

System Control er/Bus Driver

System Controller

Prog. Comm. 1/0 (USART)

Prog Interval Timer
Prog Periph. 1/0 (PP1)

Prog. DMA Control
Prog Interrupt Control
-6800.6800 SUPPORT DEVICES—
MPU

MPU with Clock and Ram
128X8 Static Ram
Periph Inter Adapt (MC6820)
Priority Interrupt Controller
1024X8 Bit. ROM (MC68A30-8)
Asynchronous Comm. Adapter
Synchronous Serial Data Adapt
0-600 bps Digital MODEM
2400 bps Modulator
Quad 3-State Bus. Trans (MC8T26)

S 7 95
3.25
5 95

4.95

5.95
7 95

1495

995

1995

1995

-MICROPROCESSOR MANUALS

M-Z80 User Manual
M -CD Pi 802 User Manual
M-2650 User Manual

S7.50

7.50

5.00

$14.95

24.95

5.95
7.49

12.95

14.95

7.95

9.95
1295
1495

2.25

MICROPROCESSOR CHIPS-MISCELLANEOUS -

280(780C) CPU

Z80A(780-1) CPU
C0P1802 CPU

2650 MPU

6502
8035

TMS9900JL

8 Bit MPU w/clock, RAM. 1/0 lines
CPU

S14 95

16.95
1995

19.95

11.95

19.95
19.95

MM500H

MM503H

MM504H

MM506H

MM510H

MM5016H

2504 T

2518

2522

2524

2525

2527

2528

2529
2532
3341
74LS670

Dual 25 Bit Dynamic
Dual 50 Bit Dynamic
Dual 16 Bit Static
Dual 100 Bit Static
Dual 64 Bit Accumulator
500/512 Bit Dynamic
1024 Dynamic
Hex 32 Bit Static
Dual 132 Bit Static
512 Static
1024 Dynamic
Dual 256 Bit Static
Dual 250 Static
Dual 240 Bit Static
Quad 80 Bit Static
Rio

4X4 Register File (TriState)

UARTS

2513(2140)

2513(3021)

2516

MM5230N

Character Generator upper case)
Character Generator(lower case)
Character Generator
2048-Bit Read Only Memory

59.95
9 95

10.95
1.85

1101

256X1

Static

SI 49

1103

1024X1

Dynamic

.99

2101(8101)

256X4

Static

395

2102

1024X1

Static

1.75

21L02

1024X1

Static

1.95

2111(8111)

256X4

Static

395

2112

256X4

Static MOS

4.95

2114

1024X4

Static 450ns

7 95

2114L

1024X4

Static 450ns low power

10.95

2114-3

1024X4

Sialic 300ns

1095

2114L-3

1024X4

Static 300ns low power

11.95

5101

256X4

Static

7.95

5280/2107

4096X1

Dynamic

495

7489

16X4

Static

1.75

74S200

256X1

Static Tristate

495

93421

256X1

Static

295

UPD414

4K

Dynamic 16 pin

4 95

(MK4027)

UPD416

16K

Dynamic 16 pin 250ns

995

(MK4116)

TMS4044-

4K

Static

14.95

45NL

TMS4045

1024X4

Static

1495

2117

16,384X1

Dynamic 350ns
(house marked)

9.95

MM5262

2KX1

Dynamic

4/1.00

1702A

2048

FAMOS

S5.95

2716INTEL

16K*

EPROM

59.95

TMS2516

16K-

EPROM

49.95

2.95

2.95

4.00

4.00

295

A-Y-5-1013 30K BAUD

(2716)
TMS2532
2708
2716 T.l

5203

6301-1(7611)

6330 1(7602)

82S23

82S115

82S123

74186

74188

74S287

•Requires single *5V power supply
4KX8 EPROM

8K EPROM

16K" EPROM

3 voltages. -5V. +5V. +1ZV
FAMOS

Tristate Bipolar
Open C Bipolar
Open Colieclor

32X8

4096

32X8

Tristate

TTL Open Collector
TTl Open Collector
Static

3.95
1995
395
9 95
3.95

JE600 HEXADECIMAL
ENCODER KIT

FEATURES:

• Full 8 bit latched output lor micro-
processor use

• 3 User Define keys with one being bi-
stable operation

• Oebounce circuit provided for an 19
keys

• LED readout to verity enmes

• Easy interfacing with standard 16 pin
1C connector

• Only -rSVDC reouired tor operations

FULL 8 BIT LATCHED OUTPUT— 19 KEYBOARD

The JE600 Encoder Keyboard provides two separate hexadecimal
digiis produced from sequential key entries to allow direct prog-
ramming Jot 8 bil microprocessor or 8 bit memory circuits Three
(3) additional keys are provided lor user operations with one having
a bistable output available The outputs are latched and monitored
with LED readouts Also nduded is a key entry strobe

JE600 $59.95

Hexadecimal Keypad only $14.95

DIGITAL

THERMOMETER KIT

• Dual sensors— switching control for in-
door/outdoor or dual monitoring

■Continuous LED .8" ht. display

• Range: -40°F to 199°F / -40°C to 100°C
■Accuracy: ±1° nominal

■Set for Fahrenheit or Celsius reading
•Sim. walnut case AC wall adapter incl.

• Size: 3-1 /4"H x6-5/8' Wx 1 -3/8"D

JE300 $39.95

62-Key ASCII Encoder Keyboard Kit

FEATURES:

•60 Keys generate the full 128 char-
acters, upper and lower case ASCII
set

• Fully buffered

• 2 user-define keys provided for
custom applications

• Caps lock for upper case only
alpha characters

• Utilizes a 2376 (40 pin) encoder
read only memory chip

The JE610 62-Key ASCII Encoder Keyboard • Outputs directly compatible with
Kit can be interfaced into most any com- TTL/DTL or MOS logic arrays
puter system. The JE610 Kit comes com- • Easy interfacing with a 16-pin dip
plete with an industrial grade keyboard or 18-pin edge connector
switch assembly (62 keys), IC's, sockets,

connector, electronic components and a ICAIA £*70 AC

double-sided printed wiring board. The y/Ti7v

keyboard assembly requires +5V @ 150mA moanc

and —12V @ iOmA for operation. 62-Key Keyboard only . . $34.95

hickok LX303 Portable LCD Digital Multimeter

•Bib > inch high, 3'i Digit Liquid CryiUl DitpUy • Over 200 Hours of operation with a 9V battery

• Automatic zero, polarity and over range indication • tOOmV DC F S wn-.itivity • I s . basic accuijcy

• 19 ranges and functions • Rugged Cycolac : case and removable covei. stoics test lead set

• Full one year nwianty

SPECIFICATIONS OC volt. 15 rangnl O ln»V to lOOOV Accwxy IQ 5% •<*> -O S'. I s Inpul mped IOmU

~T, ! l AC Volts taOMi to BhHal' O IV ro 600V. Accuracy 1 1 0*. nti, 10 < , l-7rt*e»« at 5VHrl.Mj. input 600V

Resistance 16 Lon Knm> Benges) O 1 to .’OAt f! Accuracy ’OV. ..Ig 10 5% I t 111 V. 'rta on 20M Si .angel
' *» " \ input prutn. lad lu 120V AC all i»noei

DC Currant 16 can«Ml 0 1 nA K, I OOi A. Accuracy * I O*. nig • 0 fi* . ' i

Oimansions and Waglilt 5 T.Q" a 3-3.8 1 * 1 3 4 8 or POWER 9V battery Innt nvluderll or Hekok AC ertapwr,

READ RATE 2 /lac

LX303 Digital Multimeter $74.95

DESCRIPTION PRICE

RC-3 115V AC ADAPTER 7.50

CC 3 PADDED CARRYING CASE 7.50

VP-10 X10 DC PROBE ADAPTER (Up to 10K) 14.95

VP-40 40kV DC PROBE 35.00

CS-1 10 Amp DC Current Shunt 14.95

$10.00 Min. Order — U.S. Funds Only Spec Sheets — 25*

Calif. Residents Add 6% Sales Tax 1980 Catalog Available - Send 41* stamp

Postage - Add 5% plus $1 Insurance (if desired)

„ ^ J1 PHONE

%0 oG % l ameco w°e R l D c E o R m S e

CATALO^^ (415) 592-8097

MAIL ORDER ELECTRONICS - WORLDWIDE
1355 SHOREWAY ROAD, BELMONT, CA 94002
ADVERTISED PRICES GOOD THRU JANUARY

The Incredible
Pennywhistle 103’

$139.95

Kit Only

The Pennywhistle 103 is capable of recording data to and from audio tape without
critical speed requirements lor the recorder and it is able to communicate directly with
another modern and terminal for telephone "hamming" and communications. In
addition, it is free of critical adjustments and is built with non -precision, readdy available
pads.

Oata Transmission Method Frequency-Shift Keying, full-duplex (half-duplex

selectable)

Maximum Data Rate 300 Baud

Data Format Asynchronous Serial (return to mark level required

between each character).

Receive Channel Frequencies . . .2025 Hz for space; 2225 Hz lor mark
Transmit Channel Frequencies . .Switch selectable: Low (normal) = 1070 space.

1270 mark: High - 025 space. 2225 mark.

Receive Sensitivity 46 dbm accoustically coupled

Transmit Level -15 dbm nominal. Adjustable from 6 dbm

to -20 dbm

Receive Frequency Tolerance . . .Frequency reference automatically adjusts to
allow for operation between 1800 Hz and 2400 Hz.

Digital Data Interface EIA RS-232C or 20 mA current loop (receiver is

optoisolated and non polar)

Power Requirements 120 VAC. single phase. 10 Watts

Physical All components mount on a single 5' by 9*

printed circuit board All components included.
Requires a V0M, Audio Oscillator. Frequency Counter and/or Oscilloscope to align

TRS-80

16K Conversion Kit

Expand your 4K TRS-80 System to 16K.

Kit comes complete with:

* 8 each UPD416-1 (16K Dynamic Rams ) 250NS

* Documentation for conversion

TRS-16K $75.00

JUST WRAP"

• 30 AWG wire •.025" square posts

• Daisy chain or • Built-in cut off
point-to-point • Includes 50 ft. wire

• No stripping or slitting required-
just wrap

JW-1-B

Blue

$14.95

JW-1-W

White

14.95

JW-1-Y

Yellow

14.95

JW-1-R

Red

14.95

JUST WRAP' Replacement Wire

R-JW-B

Blue

. . . 50 ft. roll

. . . $2.98

R-JW-W

White . . . .

. . . 50 ft. roll

. . . 2.98

R-JW-Y

Yellow . . .

. . . 50 ft. roll . . . .

. . . 2.98

R-JW-R

Red

. . . 50 ft. roll

. . . 2.98

JUST WRAP' Unwrap Tool $3.49

JUST WRAP' Kit •®° 1 ^ a wir b e l,J *' vvhite ' red

•JUST WRAP Tool • Unwrapping Tool

JWK-6 $24.95

Vacuum Vise

Vacuum-based light-duty
vise for small components
and assemblies. ABS con
struction. 1)4” jaws, 1)4”
travel. Can be permanently

$3.49

EPROM

Erasing

Lamp

•Erases 2708, 2716, 1702A, 5203Q, 5204Q. etc.

• Erases up to 4 chips within 20 minutes.

•Maintains constant exposure distance of one inch
•Special conductive foam liner eliminates static build-up

• Built-in safety lock to prevent UV exposure

• Compact - only 7-5/8” x 2-7/8" x 2"

• Complete with holding tray for 4 chips

UVS-11E S69.95

Micro- Miniature
Joystick

•2 each 100K pots (Linear
A Taper)

W • Printed Circuit Board
. | Mount

I'J; I? • Size: 1 ” x 1-3/1 6" x 1-3/16"

Micro-Miniature Joystick ... $4.95 y

214 Microcomputing January 1980

IN

A o*; 1

7400 TTL

SN7400N
SN7401N
SN7402N
SN 7403*4
SN7404N
SN7405N
SN7406N
SN7407N
SN7408N
SN7409N
SN7410N
SN7411N
SN7412N
SN7413N
SN7414N
SN7416N
SN7417M
SN7420N
SN7421N
SN7422N
SN7423N
SN7425N
SN7426N
SN7427N
SN7429N
SN7430N
SN7432N
SN7437N
SN7438N
SN7439N
SN7440N
SN7441N
SN7442N
SN7443N
SN7444N
SN7445N
SN7446N
SN7447N
SN7448N
SN7450N
SN7451N
SN7453N
SN7454N
SN74S9A
SN7460N

.25

.20

C04000
C04001
CD4002
C04006
C04007
CD4009
C04010
CD4011
CD4012
C 0401 3
CD4014
CD4015
CD4016
C04017
C0401B
C04019
CD4020
CD4021
CD4022
C04023
CD4024
CD4025
CD4026
CO4027

74C00

74C02

74C04

74C08

74C10

74C14

74C20

74C30

74C42

74C48

74C73

74C74

78MG

LM106H

LM300H

LM301CN/H

LM302H

LM304H

LM305H

LM307CN/H

LM308CN/H

LM309H

LM309K

LM310CN

LM311N/H

LM312H

LM317K

LM318CN/H

LM319N

LM320K-5

LV320K-5 2

LM320K-12

LM320K-15

LM320K-18

LM320K-24

LM320T 5

LM320T-52

LM320T-8

LM320T-12

LM320T-15

LM320T-18

LM320T-24

LM323K-5

LM324N

LM339N

LM340K-5

LM340K-6

LM340K-8

LM340K-12

LM34QK 15

74LS00
74LS01
74LS02
74LS03
74LS04
74LS05
74LS08
74LS09
74LS10
74LS11
74LS13
74LS14
74LS15
74LS20
74LS21
74LS22
74LS26
74LS27
74LS28
74LS30
74LS32
74LS37
74LS40
, 74LS42

SN7470N

SM7472N

SN7473N

SN7474N

SN7475N

SN7476N

SN7479N

SN7480N

SN7482N

SN7483N

SN74B5N

SN7486N

SN7489N

SN7490N

SN7491N

SN7492N

SN7493N

SN7494N

SN7495N

SN7496N

SK7497N

SN74100N

SN74107N

SN74109N

SN74116N

SN74121N

SN74122N

SN74123N

SN74125M

SN74126N

SN74132N

SN74136N

SN74141N

SN74142N

SN74143N

SN74144N

SN74145N

SN74147N

SN74148N

SN74150N

SN74151N

SN74152N

SN74153N

SN74154N

SN74155N

SN74156N

SN74157N

35

.59

1.95

.35

.39

C/MOS

C04029
C04030
C04035
C04040
C04041
C04042
C04043
CD4044
CO 4 046
CD4047
CD4048
CD4049
CD4050
C04051
C04053
C04056
CD4059
CD4060
CD4066
CD4068
C04069

99
1.19
1 25
99
89
.89
1.79
2.50
135

74C00

74C85

74C90

74C93

74C95

74C107

74C151

74C154

74C157

74C160

74C161

290
3.00
2 IS
2.49
2 49

LINEAR

LM340K-18 1.35

LM340K-24 1.35

LM340T-5
LM340T-6
LM340T-8
LM340T-12 1.25

LM340T-15 1.25

LM340T-18 1.25

LM340T-24 125

LM358N
LM370N
LM373N
LM377N
LM380N
LM380CN
LM381N

1.25

1 00

3 25
400
1.25

NE501N

NE510A

NE529A

NE531H/V

NE536T

NE540L

NE544N

NE550N

NE555V

NE556N

NE560B

NE561B

NE562B

NE565N/H

NE566CN

NE567V/H

NE570N

LM703CN/H

LM709N/H

1.79
8.00
6.00
4 95

3.95
600
6.00

4.95

5.00
5.00
5.00
1.25
1 75

74LS00TTL

74LS47 89
74LS51 .29
74LS54 .29
74LS55 29
74LS73 45
74LS74 .45
74LS75 59
74LS76 45
74LS78 49
74LS83 89
74LS85 1.25
74LS86 45
741S90 59
74LS92 .75
74LS93 .75
74LS95 99
74LS96 1.15
74LS107 .45
74LS109 .45
74LS112 45
74LS123 1.25
74LS125 89
74LS132 99
74LS136 .49

SN74160N

SN74161N

SN74162N

SN74163N

SN74164N

SN74165N

SN74166N

SN74167N

SN74170N

SN74172N

SN74173N

SN74174N

SN74175N

SN74176N

SN74177N

SN74179N

SN74180N

SN74181N

SN74182N

SN74184N

SN74185N

SN74186N

SN74188N

SN74190N

SN74191N

SN74192N

SN74193N

SN74194N

SN74195N

SN74196N

SN74197N

SN74198N

SN74199N

SN74S200

SN74251N

SN74279N

SN74283N

SN74284N

SN74285N

SN74365N

5N74366N

SN74367N

SN74368N

SN74390N

SN74393N

C 04070

C04071

C04072

CD4076

CD4081

CD4082

C04093

C04098

MC14409

MC14410

MCI 44 11

MC14419

MCI 4433

MCI 4506

MCI 4507

MCI 4562

MCI 4583

CD4508

CO4510

C04511

CD4515

CD4518

CD4520

C04566

249
14 95
1495

14.95
4 95

19.95

74C163

74C164

74C173

74C192

74C193

74C195

74C922

74C923

74C925

74C926

80C95

80C97

1 50

100

LM710N
LM711N
LM723N/H
LM733N
LM739N
LM741CN/H 35
LM741-14N .39

LM747N/H 79
LM748N/H .39
LM1310N 1 95

LM1458CN/H .59
MC1488N 1.95

MC1489N 1.95

LM1496N .95

LM 1556V 1.75

MC1741SCP 3.00
LM2111N 195

LM2901N 295

LM3053N 1.50

LM3065N 1.49

LM39O0N(3401) 59
LM3905N 1.49

LM3909N
MC5558V
80389
LM75450N
75451 CN
75452CN
75453CN
75454CN
75491CN
75492CN
75493N
75494CN
RC4136
RC4151
RC4194
RC4195

1.25

59

4.95

74 LSI 38
74LS139
74LS151
74LS155
74LS157
74LS160
74LS161
74LS162
74LS163
74LS164
74LS175
74LS181
74LS190
74LS191
74LS192
74LS193
74LS194
74LS19S
74LS253
74LS257
74LS258
74LS260
74LS279
74LS367
74LS368
74LS670

JJL

Q Cromemco

incorporated

Tl I- ART Cromcmco's TU-ART
* ^ r\K\ M digital interface Is a
pv» ;x_| convenient interface
LIlQllal for CRTtermlnals. line
- r printers, modems, and

\ni(>Y\7\CC> other devices. Has 2
llllcl lace serial I/O ports, 2 8-bit
parallel I/O ports, and 10 independent pro-
grammable interval timers. Baud rates arc
software-selectable from 110-76,800 baud.
Has vectored prioritized interrupts so it is
able to support the powerful vectored in-
terrupt structure of aZ-80microprocessor.
10 interval timers w/real-tlme capability.

Serial I/O Pont.

Mo. ol pom 2

I/O levels RS 232or 20mA curr, loop
Low baud r mill I- 1 10-9600 baud
(software selectable]

High baud range 880 76.800 baud
(software Ml re table)

Parallel I/O Port*

Mo. of ports: 2 Input pons: 8 bits
Output ports 8 bits
Input load: one TTL equivalent
Output Drive 20 TTL loads

Interval Timers:

No. ol timers 10
Timer range: 0-16.32 msec
i software selectable)

Tuner resolution 64 microteconds
Vectored Interrupts:

Mo restart locations (8080 model 8
Mo. restart Iocs. IZ-80 model 6b. 536
Pnonti/jtion ol TU-ART ports,
rioritired

tn for multiple TU-ART*

General Information:

UART Type 5601 But S I 00

Power requirement* 48V P 1.0A
♦ 1BV 9 80mA 18V@40mA

Operating environment: 0'55*C

TRT-W

(Assembled) $295.00

DISCRETE LEDS

.200 dla.

XC556R red 5/$1

XC556G green 4/$1

XC556Y yellow 4/SI

XC556C clear 4/SI

200~ dla.

XC22R red 5/$1

XC22G green 4/$1

XC22Y yellow 4/SI

.170" dla.

MV10B red 4/S1

085~ dla.

MV50 red 6/SI

INFRA-RED LED

1/4"x1/4"x1/16" flat
5/SI

XC209R

XC209G

XC209Y

XC526R

XC526G

XC526Y

XC526C

XC111R

XC111G

XC111Y

XC111C

.125" dla.
red
green
yellow
.185 die.
red
green
yellow
clear

.190’ dla.
red
green
yellow
clear

5/SI

4/SI

4/SI

5/S1

4/$1

4/SI

4/SI

5/SI

4/SI

4/SI

4/SI

DISPLAY LEDS

TIMEX T1001
LIQUID CRYSTAL DISPLAY
CLASS II

FIELD EFFECT

86:06

4 0IGIT .5" CHARACTERS
THREE ENUNCIATORS
2.00" X 1.20" PACKAGE
INCLUDES CONNECTOR

Tl 001 -Transmissive $7.95

T1001 A-Reflective 8.25

TYPE
MAN 1
MAN 2
MAN 3
MAN 4
MAN 7G
MAN 7Y
MAN 72
MAN 74
MAN 82
MAN 84
MAN 3620
MAN 3630
MAN 3640
MAN 4610
MAN 4640
MAN 4710
MAN 4730
MAN 4740
MAN 4810
MAN 4840
MAN 6610
MAN 6630
MAN 6640
MAN 6650
MAN 6660
MAN 6680
MAN 6710

POLARITY H

Common Anode red )

5 x 7 Dot Matrix-red .i

Common Cathode-red
Common Cathode-red
Common Anode-green
Common Anode-yellow
Common Anode-red
Common Cathode-red
Common Anode yellow
Common Cathode -yellow .1

Common Anode-orange
Common Anode-otarge s 1
Common Cathode-orange
Common Anode-orange
Common Cathode-orange -

Common Anode-red '

Common Anode-red ± 1 .'

Common Cathode-red .*

Common Anode-yellow '

Common Cathode-yellow *

Common Anode-orange-D D I

Common Anode-orange - 1 .!

Common Caihode-orange-D.D. .1

Common Cathode-orange 2 1 .!

Common Anode-orange .!

Common Cathode -orange
Common Anode-red -DD.

TYPE

MAN 6730

MAN 6740

MAN 6750

MAN 6760

MAN 6780

DL701

DL704

OL707

DL728

0L741

DL746

DL747

DL749

DL750

DL33B

FND70

FND358

FN0359

FND503

FND507

5082-7730

HDSP-3400

HDSP-3403

5082-7300

5082-7302

5082-7304

5082 7340

POLARITY

Common Anode-red 2 1
Common Cathode-red-D.D
Common Cathode-red 2 1
Common Anode-red
Common Cathode red
Common Anode -red ± 1
Common Cathode-red
Common Anode-red
Common Cathode-red
Common Anode-red
Common Anode -red 2 1
Common Anode red
Common Cathode -red ± 1
Common Cathode-red
Common Cathode-red
Common Cathode
Common Cathode ± 1
Common Cathode
Common Cathode(FN0500)
Common Anode (FN0510)
Common Anode-red
Common Anode-red
Common Cathode red
4 x 7 sgl Digit RHDP
4 x 7 Sfll Digit -LH0P
Overrange characterful)

4 x 7 Sgl Digit-Hexadecimal

1.50
19 95
19.95
15.00
22.50

RCA LINEAR

CA3C13T

CA2023T

CA303ST

CA3039T

CA3046N

CA3059N

CA3060N

CA3080T

CA3081N

.15 CA3082N
56 CA3083N
.48 CA3086N
.35 CA3089N
.30 CA3130T
25 CA3140T
25 CA3160T
85 CA3401N
.00 CA3600N

3.50

CALCULATOR

CHIPS/DRIVERS

MM5725 $2 95

MM5738 2.95

DM8864 2 00

DM8865 1.00

DM8887 . 75

0M888S .75

93/4 / seg

1 50

CLOCK CHIPS

MM5309 $4 95

MM5311 4.95

MM5312 4.95

MM5314 4.95

MM5316 6.95

MM5318 9 95

MM5369 295

MM5387/1998A 4.95

CT7001 6 95

MC1408L7

MC1408L8

MC1439L

MC3022P

MC3061P

MC4016(74416)

MC4024P

MC4040P

MC4044P

1-24

*17

49

$30

8 pin LP
14 pin LP
16 pin LP
18 pin LP
20 pin LP
14 pin ST
16 pin ST
18 pin ST
24 pin ST
8 pin SG
14 pin SG
16 pm SG
18 pm SG

20 pin WW ,85 .79

.27

32

27

.25

.30

.42

.24

1C SOLDERTAIL — LOW PROFILE (TIN) SOCKETS

25-49 50-100 1-24

■■■ MAMBttl 22 Pin LP $-37
24 pin LP 36

.21 20 •PP 28 pin LP <5

28 . 27 36 pin IP 60

32 30 SOLDERTAIL STA NDARD (T IN) 40 P jnLP 63

28 pin ST $ 99
36 pin ST 139
40 pin ST 1-59

SOLDERTAIL STANDARD (GOLD)

24 pin SG * 70

28 pm SG 1-10
36 pin SG 165
40 pin SG 1-75

22 pin WW $ .95
24 pm WW 1.05
28 pin WW 1.40
36 pin WW 159
40 pm WW 175

25-49

.36

WIRE WRAP SOCKETS
(GOLD) LEVEL #3

1.15

1.30

1 10
1.30
1.40

1/4 WATT RESISTOR ASSORTMENTS -5%

10 OHM 12 OHM 15 OHM 18 OHM 22 OHM

ASST. 1

5 ea

27 OHM

33 OHM

39 OHM

47 OHM

56 OHM

50 PCS

$1.75

68 OHM

82 OHM

100 OHM

120 OHM

150 OHM

1.75

ASST. 2

5 81.

180 OHM

220 OHM

270 OHM

330 OHM

390 OHM

50 PCS

470 OHM

560 OHM

680 OHM

820 OHM

IK

1.75

ASST. 3

Sea.

1.2K

1.5K

1.8K

2.2K

2.7K

50 PCS

3.3K

3.9K

4.7K

5.6K

6.BK

1.75

ASST. 4

5 ea.

8.2K

10K

12K

15K

18K

50 PCS

22K

27K

33K

39K

47K

1.75

ASST. 5

Sea.

56K

6BK

82K

100K

120K

50 PCS

150K

180K

220K

27QK

330K

1.75

ASST. 6

Sea

390K

470K

560K

680K

820K

50 PCS

IM

1.2M

1.5M

I.8M

2.2M

1.75

ASST. 7

5 ea

2.7M

3.3M

3.9M

4.7M

5.6M

50 PCS

ASST. 8R

Includes Resistor Assortments 1 -7 (350 PCS.)

$9.95 ea

$10.00 Min. Order - U.S. Funds Only Spec Sheets - 25^

Calif. Residents Add 6% Sales Tax 1980 Catalog Available - Send 414 stamp

Postage— Add 5%plus$1 Insurance (if desired)

PHONE
ORDERS
WELCOME
(415) 592-8097

ELECTRONICS

MAIL ORDER ELECTRONICS - WORLDWIDE
1355 SHOREWAY ROAD, BELMONT, CA 94002
ADVERTISED PRICES GOOD THRU JANUARY

AY -5-9100
AY -5-9200
AY -5-9500
AY -5-2376
HD0165
74C922
74C923

TELEPHONE/KEYBOARD CHIPS

Push Button Telephone Dialler
Repertory Dialler
CMOS Clock Generator
Keyboard Encoder (88 keys)
Keyboard Encoder (16 keys)
Keyboard Encoder (16 keys)
Keyboard Encoder (20 keys)

$14.95

14.95

4.95

14.95

7.95
7.95
6.25

ICM7045

ICM7205

ICM7207

ICM7208

ICM7209

ICM CHIPS

CMOS Precision Timer
CMOS LED Stopwatch/Timer
Oscillator Controller
Seven Decade Counter
Clock Generator

24.95

19.95
7.50

19.95

6.95

NM0S READ ONLY MEMORIES

MCM6571

128 X 9 X 7 ASCII Shifted with Greek

13.50

MCM6574

128 X 9 X 7 Math Symbol & Pictures

13.50

MCM6575

128 X 9 X 7 Alpha Control Char Gen

13.50

TL074CN

TL494CN

TL496CP

11C90

95H90

4N33

MK50240

DS0026CH

TIL308

MM5320

MM 5330

LD110/111

MC14433P

MISCELLANEOUS

Quad Low Noise bi-fet Op Amp
Switching Regulator
Single Switching Regulator
Divide 10/11 Prescaler
Hi-Speed Divide 10/11 Prescaler
Photo-Darlington Opto-lsolator

2.49

4.49

1.75

19.95

11.95

3.95
17.50

3.75

Nngton ___

Top Octave Freq Generator
5Mhz 2 -phase M0S clock driver
.27" red num. display w/integ. logic chip 10.95
TV Camera Sync. Generator 14.95

4% Digit DPM Logic Block (Special) 3.95
3V4 Digit A/D Converter Set 25.00/set

3 ft Digit A/D Converter 13. 95

UTRONIX ISO-LIT 1

Photo Transistor Opto-lsolator
(Same as MCT 2 or 4N25)

49 i each

SN 76477

SOUND GENERATOR
Generates Complex Sounds
Low Power - Programmable

$3.95 each

TV GAME CHIP AND CRYSTAL

AY -3-8500-1 and 2.01 MHZ Crystal (Chip & Crystal

XR205

XR210

$8 40
4.40
4.40

EXAR

XR2242CP

XR2264

XR2556

1.50

4.25

3.20

XR320

1.55

XR2567

2.99

XR-1555

1.50

JE2206KB 19.95

XR3403

1.25

XR555

.39

XR1800

3.20

XR4136

1.25

XR556

99

XR2206

4.40

XR4151

395

XR567CP

.99

XR2207

3.85

XR4194

4.95

XR567CT

1.25

XR2208

5.20

XR4202

3.60

XR1310P

1.95

XR2209

1.75

XR4212

205

XR1468CN

3.85

XR2211

5.25

XR4558

.75

XR1488

195

XR2212

4.35

XR4739

1.15

XR1489

1.95

XR2240

3.45

XR4741

1.47

ninnFS

TYPE VOLTS W

PRICE

1N4002

100 PIV 1 AMP

12/1 00

TYPE

VOLTS W

PRICE

1N4003

200 PIV 1 AMP

12/1.00

1N746

3.3

400m

4/1.00

1N4004

400 PIV 1 AMP

12/1 00

1N751

5.1

400m

4/1 00

1N4005

600 PIV 1 AMP

10/1 00

1N752

5.6

400m

4/1.00

1N4006

800 PfV 1 AMP

10/1.00

1N753

6.2

400m

4/1.00

1N4007

1000 PIV 1 AMP

10/1.00

1N754

6.8

400m

4/1 00

1N360O

50 200m

6/1.00

1N757

1 1

400m

4/1 00

1N4148

75 10m

15/1 00

1N759

120

400m

4/1.00

1N4154

35 10m

12/1 00

1N959

8.2

400m

4/1.00

1N4733

5.1 1w

28

1N965

15

400m

4/1.00

1N4734

56 1w

28

1N5232

5.6

500m

28

1N4735

6.2 1w

28

1N5234

6.2

500m

28

1N4736

68 1w

28

1N5235

6 8

500m

28

1N4738

8.2 1w

28

1N5236

7.5

500m

28

1N4742

12 1w

28

1N5242

12

500m

28

1N4744

15 1w

28

1N5245

15

500m

28

INI 183

50 PIV 35 AMP

1 60

1N456

25

40m

6/1 00

IN1 184

100 PIV 35 AMP

1.70

150

7m

6/1.00

INI 185

150 PIV 35 AMP

1.70

1N485A

180

10m

5/1.00

IN1 186

200 PIV 35 AMP

1.80

1N4001

50 PIV 1 AMP

12/1 00

IN1 188

400 PIV 35 AMP

3.00

SCR AND FW BRIDGE RECTIFIERS

C36D

ISA <& 400V

SCR(2N1849)

SI .95

C36M

35A (a 600V

SCR

1.96

2N2328

1.6A <& 300V

SCF

1

.50

MDA 980 1

12A(& 50V

FW BRIOGE REC.

1.95

MDA 980-3

12A (q 200V

EW BRIDGE HEC

1.95

.50

TRANSISTORS 2N3904

4/1.00

MPSA05

.30

2N3055

89

2N3905

4/1.00

MPSA06

5/1.00

MJE3055

1.00

2N3906

4/1.00

TIS87

6/1.00

2N3392

5/1.00

2N4013

3/1 00

TIS98

6/1.00

2N3398

5/1.00

2N4123

6/1 00

40409

1.75

PN3567

3/1.00

PN4249

4/1 00

40410

1.75

PN3568

4/1.00

PN4250

4/1 00

40673

1.75

PN3569

4/1.00

2N4400

4/1.00

2N918

4/1.00

MPS3638A

5/1.00

2N4401

4/1 00

2N2219A

2/1 00

MPS3702

5/100

2N4402

4/1 00

2N2221A

4/1.00

2N3704

5/1.00

2N4403

4/1.00

2N2222A

5/1 00

MPS3704

5/1 00

2N4409

5/1.00

PN2222 Plastic

7/1.00

2N3705

5/1.00

2N5086

4/1 00

2N2369A

4/1.00

MPS3705

5/1.00

2N5087

4/1 00

MPS2369

5/1.00

2N3706

5/1.00

2N5088

4/1.00

2N2484

4/1.00

MPS3706

5/1.00

2N5089

4/1 00

2N2906

4/1.00

2N3707

5/1.00

2N5129

5/1 00

2N2907

5/1.00

2N3711

5/1.00

PN5134

5/1.00

PN2907 Plaslic

7/1.00

2N3724A

.65

PN5138

5/1.00

2N2925

5/1.00

2N3725A

1.00

2N5139

5/1.00

MJE2955

1 25

2N3772

2.25

2N5210

5/1 00

2N3053

2/1.00

2N3823

1.00

2N5449

3/1.00

2N3903

5/1.00

2N5951

CAPACITOR £

OISC CAPACITORS

L3 1JL22 M_

CORNER

10 pt

.05

.04

03

OOVF

035

22 p«

.05

.04

.03

0047#tF

.05

.04

035

47 pf

.05

.04

.03

,oi M f

05

.04

.035

100 pi

.05

.04

.03

022 M F

.06

.05

.04

220 pf

.05

.04

03

.047mE

.06

05

.04

470 Of

.05

.04

035

.12

.09

.075

100 VOLT MYLAR FILM CAPACITORS

.001 ml

.12

.10

.07

022mf

.13

.11

.08

0022

.12

.10

.07

.047mf

.21

.17

.13

.0047mf

.12

.10

.07

,1mf

.27

.23

.17

01 mf

.12

10

.07

22mf

.33

.27

.22

•1/35V
15/35V
. 22/35V
. 33/35 V
47/35V
68/35V
1.0/35V

47/50 V

1 0/50V

3.3/50V

4.7/2SV

10/25V

10/50V

22 /25V

22/S0V

47/25V

4 7 /50V

100/25V

100/50V

220/25V

220/50V

470/25V

1000/16V

2200/16V

-f-20% OIPPEO TANTALUMS (SOLID) CAPACITORS

.28 23 .17 1.5/35V .26 .21

.28 .23 .17 2.2/35V .35 Jl 21

.28 .23 .17 3.3/25V .35 J1 .27

.28 .23 .17 4.7/25V .33 .28 .23

.28 . 23 .17 6.8/25V .49 .45 .35

.28 .23 .17 15/25V -75 ^8 S 9

.28 .23 .17 22/6V -75 .60 .50

MINIATURE ALUMINUM ELECTROLYTIC CAPACITORS

.15 .13

16 .14 .12

.10 47/25V

.11 .47/50V

.09 1.0/16V

.10 1.0/25V

.10 1.0/50V

4.7/1 6V
4.7/25V
4.7/50V
.1/ .15 10/16V

.21 .19 10/25V

20 18 10/50V

30 .28 47/50V

28 25 100/16V

41 .38 100/25V

.29 .27 100/50V

.50 .45 220/16V

62 55 470/25V

Radial Lead

.15 13

4^ Reader Service— see page 227

Microcomputing January 1980 215

THERE'S NO NEED TO COMPROMISE
WITH COMPUPRO .

We don't compromise on our designs so you don't have to compromise on
performance. Our expanded S-100 line is the answer to the needs of professional
computer users — just ask the dealers who specify our components when making up
systems for scientific, commercial, and industrial applications. Speaking of dealers,

Godbout products (under the CompuPro ,M name) are now available from more dealers
than ever before . . . which makes it even easier for you to experience Godbout quality
in person. Shop around, compare prices, and compare specs: we think we know whose
products will earn a space in your computer.

MORE NEWS FROM THE MEMORY LEADER.

This month, we spotlight Econoram XIIIA — an S-100 bank select board that’s
completely compatible with Alpha Micro, Cromemco, and similar systems (all 8
bits of the data word are available for bank select). Addressable on 4K bound-
aries. Available in 16K, 24K, or 32K configurations; see list below (which in-
cludes our other popular memories) for prices.

All Econoram* memories are fully static, run with 5 MHz (or slower) systems,
include a 1 year limited warranty, and generally come in three different con-
figurations to suit your needs — unkit, assembled and tested, or qualified under
our high-reliability Certified System Component program (200 hour burn-in, im-
mediate replacement in event of failure within 1 year of invoice date).

Name

Buss & Notes

Unkit

Assm

CSC

8K Econoram IIA

S-100

$149

$179

$239

16K Econoram IV

S-100

$269

$329

$429

16K Econoram VIIA-16

S-100

$279

$339

$439

24K Econoram VIIA-24

S-100

$398

$485

$605

16K Econoram IX-16

Dig Grp

$319

$379

n/a

32K Econoram IX-32

Dig Grp

$559

$639

n/a

32K Econoram X

S-100

$529

$649

$789

32K Econoram XI

SBC/BLC

n/a

n/a

$1050

16K Econoram XIIIA-16

S-100 (1)

$329

$419

$519

24K Econoram XIIIA-24

S-100 (1)

$429

$539

$649

32K Econoram XIIIA-32

S-100 (1)

$559

$699

$849

16K Econoram XIV

S-100 (2)

$299

$359

$459

16K Econoram XV-16

H8 (3)

$329

$395

n/a

32K Econoram XV-32

H8 (3)

$599

$729

n/a

1 6K x 1 6 or 32K x 8 Econoram XVI — coming soon!

(1) Bank select board addressable on 4K boundaries.

(2) Extended addressing (24 address lines). Single block addressable on 4K boundaries.

(3) Bank select option for implementing memory systems greater than 64K.

i Econoram is a trademark of Godbout Electronics.

THE GODBOUT COMPUTER BOX:

$259 desk top, $299 rack mount (introductory price)

The ideal home for your computer. Includes dual AC outlets and fuseholder on
rear, power switch, heavy-duty line filter, black anodized front panel (with tex-
tured vinyl painted cover for desk top version); pre-drilled base accepts our
high-performance S-100 motherboards or types by Vector, California Digital,
and others. Rack mount version includes slides for easy pull-out from rack for
maintenance or board changing. You can even cut a hole in the front panel and
put in a mini-floppy ... all in all, this is a functional, versatile, and handsome
enclosure that does justice to the finest computer systems.

2708 EROM BOARD $85 unkit

4 independently addressable 4K blocks, with dipswitch selectable jump start
built right into the board. Includes all support chips and manual, but does not
include EROMs.

ACTIVE TERMINATOR BOARD $34.50 kit

Plugs into any S-100 motherboard (although ours don’t need it) to reduce ring-
ing, crosstalk, noise, and other buss-related problems.

LIMITED QUANTITY SPECIAL:

PASCAL/M“ MEMORY!

PASCAL can give a microcomputer with CP/M more power than many minis!
And for a limited time only, you can buy an assembled 32K Econoram X, plus our
totally standard Wirth PASCAL/M ,M 8" diskette, for S799 (regular combined price,
$999). Includes manual, plus Wirth’s definitive book on PASCAL; specify Z80 or
8080/8085 version. Hurry — this is an introductory special. Diskette only without
memory board: $350.

S-100 MEMORY MANAGER BOARD
$59 kit, $85 assm, $100 CSC

Now you can add bank select and extended addressing to older S-100
machines like the Altair, IMSAI, Sol, Polymorphic, etc. Either use this board
with our new extended addressing boards, or retrofit our high density
Econorams (the ones with phantom or extra qualifier lines) for use with the
Memory Manager to get up to V 2 a megabyte of memory space for your com-
puter.

DO YOU SPEAK TRS-80**?

We’ve been expanding the memory of Model 1 TRS-80** machines for over a
year now with our low power, high speed memory expansion chip set ($87.20).
Now you can use the same chip to expand memory in Apple, newer PET, Exidy
Sorcerer, and Heath H89 machines — as well as expand a 32K Model II
TRS-80** to 48K or even 64K. And if that isn’t enough memory for you, watch
this space for news on our high-density, Model II compatible 64K board with
bank select! **TRS-80 is a trademark of the Tandy Corporation.

2S "Interfacer" S-100 I/O Board
$189 unkit, $249 assm, $324 CSC

Dual RS-232 ports with full handshake; EIA232C line drivers and receivers
(1488, 1489) along with current loop (20 mA) and TTL signals on both ports. On-
board crystal controlled timebase with independently selectable Baud rate
generators for each port (up to 19.2 KBaud). Hardware UARTs.

HIGH-PERFORMANCE MOTHERBOARDS

19 slot: $174 unkit, $214 assm
12 slot: $129 unkit, $169 assm
6 slot: $ 89 unkit, $129 assm

Unkits have edge connectors and termination resistors pre-soldered in place
for easy assembly. These boards exceed the latest S-100 specs and will work
with 5 to 10 MHz CPUs. Includes true active termination, grounded Faraday
shield between all buss signal lines, and edge connectors for all slots.

3P PLUS S "Interfacer II" S-100 I/O Board
$189 unkit, $249 assm, $324 CSC

Incorporates 1 channel of serial I/O (with all the features of a port from the 2S
“Interfacer”), along with 3 full duplex parallel ports. The parallel section uses
LSTTL octal latches for latched input and output data with 24 mA drive current,
attention/enable/and strobe bits for each parallel port (with selectable polarity),
interrupts for each input port, and separate 25 pin connectors with power for
each channel along with a status port for interrupt mask and port status.

TERMS: Allow 5% for shipping
excess refunded. Cal res add
tax. VISA®/Mastercharge® : call
our 24 nr. order desk at
(415) 562-0836. COD OK with
street address for UPS. Prices
good through cover month of
magazine.

725 Wright St., Oakland Airport, CA 94614 415-562-0636

(/ G4

SEND FOR OUR
FREE CATALOGUE

216 Microcomputing January 1980

WAMECO

THE COMPLETE PC BOARD HOUSE
EVERYTHING FOR THE S-IOO BUSS

* FPB-1 FRONT PANEL BOARD. Hex Displays,

IMSAI Replaceable. PCBD $54.95

* FDC-1 FLOPPY DISC CONTROLLER BOARD

Controls up to 8 Discs. PCBD $45.00

* MEM-1A 8K BYTE 2102 RAM BOARD

PCBD $31.95

KIT 450 NSEC $141.95

* MEM-2 16K BYTE 2114 RAM BOARD

PCBD $31.95

KIT 450 NSEC $299.95

* CPU-1 8080A CPU BOARD with Vector Interrupt.

PCBD $31.95

KIT $124.95

* EPM-1 4K BYTE 1702A EPROM

PCBD $29.95

KIT LESS PROMS $59.95

* EPM-2 16K or 32K BYTE EPROM 2708 or 2176

Interchangeable.

PCBD $30.00

KIT LESS PROMS $74.95

* QMB-9 9 SLOT MOTHER BOARD

Terminated. PCBD $35.00

KIT $89.95

* QMB-12 12 SLOT MOTHER BOARD

Terminated. PCBD $45.00

KIT $115.95

* RTC-1 REALTIME CLOCK

Programmable Interrups $27.95

KIT $79.95

* PTB-1 POWER SUPPLY BOARD

PCBD $30.95

KIT LESS REGULATORS $55.95

FUTURE PRODUCTS: 80 CHARACTER VIDEO BOARD,

10 BOARD WITH CASSETTE INTERFACE.

DEALER INQUIRIES INVITED, UNIVERSITY DISCOUNTS AVAILABLE

AT YOUR LOCAL DEALER

W22

W7T7C

inc. WAMECO INC. Ill GLENN WAV #8, BELMONT, CA 94002 (415) 592-6141

€

■■I CALIFORNIA COMPUTER SYSTEMS

16K RAM BOARD Fully buffered addressable in 4K
blocks IEEE standard for bank addressing 2114 s

PCBD $26 95

Kit 450 NSEC $259.95

PT-1 PROTO BOARD Over 2.600 holes 4" regu-

lators All S-100 buss functions labeled, gold fingers
PCBD 525 95

PT-2 PROTO BOARD Similar to PT-1 except set-

up to handle solder tail sockets
PCBD $25.95

==/D

FORMERLY CYBERCOM SOLID STATE MUSIC

PB-1 2708& 2716 Programming Board with provisions
for 4K or 8K EPROM No external supplies require

textool sockets Kit $124 95

CB-1 A 8080 Processor Board. 2K of PROM 256 BYTE
RAM power on/rest Vector Jump Parallel port with

status. Kit TBD PCBD $30.95

MB-6B Basic 8KX8 ram uses 2102 type rams. S-100

buss Kit 450 NSEC. $139.95 PCBD $26 95

MB-7 16KX8. Static RAM uses u P41 0 Protection.

fully buffered. Kit $299.95

MB-8A 2708 EROM Board. S-100. 8K8X or 16 Kx8

kit without PROMS $75 00 PCBD $28 95

VB-3 80x55 VIDEO BOARD

Graphic included TBD

IO-2 S-100 8 bit parallel / 10 port. *6 of boards is for
kludging. Kit $46 00 PCBD $26 95

IO-4 Two serial I/O ports with full handshaking
20/60 ma current loop Two parallel I/O ports.

Kit $130.00 PCBD $26 95

VB-1B 64 x 16 video board, upper lower case Greek,
composite and parallel video with software, S-100.

Kit $125.00 PCBD $2695

Altair Compatible Mother Board, 11 x 11% x Vi".
Board only $39 95. With 15 connectors. $94.95

Extended Board full size. Board only $ 9.49

With connector ... $13.45

SB-1 Synthesizer Board S-100

PCBD $42 95 KIT $135.95

W7J7C/nc. WAMECO INC.

FDC-1 FLOPPY CONTROLLER BOARD will drive
shugart pertek. remic 5” & 8” drives up to 8 drives,
on board PROM with power boot up. will operate
with CPM™(not included)

PCBD $42.95

FPB-1 Front Panel IMSAI size, hex displays Byte,
or instruction single step

PCBD $47.50

MEM-1A 8KX8 fully buffered, S-100, uses 2102 type

rams. PCBD $25.95

QM-12 MOTHER BOARD. 13 slot, terminated. S-100
board only $38.75

CPU-1 8080A Processor board S-100 with 8 level
vector interrupt PCBD $26 95

RTC-1 Realtime clock board. Two independent in-
terrupts. Software programmable PCBD $23.95
EPM-1 1702A 4K Eprom card PCBD $25.95

EPM-2 2708/2716 16K/32K

EPROM CARD PCBD $25.95

QM-9 MOTHER BOARD. Short Version of QM-12.

9 Slots PCBD $30 95

MEM-2 16K x 8 Fully Buffered

2114 Board PCBD $26 95

PTB-1 POWER SUPPLY AND TERMINATOR BOARD
PCBD $25.95

8080A $9 95 2708 $8.99

8212 2.49 2114 (450 NS) low pwr 5.99

8214 4.49 2114 (250 NS) low pwr 6.99

8224 3.49 2102A-4L 1.20

P. O. Box 424 • San Carlos, California 94070

Please send for 1C, Xistor
and Computer parts list ^^39

JAN. SPECIAL SALE
ON PREPAID ORDERS

(Charge cards not included on this offer)

FPB-1 with MIKOS #14

Front Panel Kit $119.95

8Kx8 Ram 450 NSEC fully buffered, 2.5
amps typical $99.99

MIKOS PARTS ASSORTMENT
WITH WAMECO AND CYBERCOM PCBDS

MEM-2 with MIKOS *7 16K ram

with L21 14 450 NSEC $249 95

MEM-2 with MIKOS *13 16K ram

with L2114 250 NSEC $279 95

MEM-1 with MIKOS #1 450 NSEC 8K

RAM $119 95

CPU-1 with MIKOS #2 8080A CPU $94.95

MEM-1 with MIKOS #3 250 NSEC 8K

RAM $144 95

QM-12 with MIKOS #4 13 slot mother

board $89.95

RTC-1 with MIKOS #5 real time clock $54.95

EMP-1 with MIKOS #10 4K 1702 less

EPROMS $49 95

EPM-2 with MIKOS #11 16-32K EPROMS

less EPROMS $59 95

QM-9 with MIKOS #12 9 slot mother

board $79.95

FPB-1 with MIKOS *14 all parts

for front panel $134.95

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY PRIME
PARTS KITS INCLUDE ALL PARTS LISTED AS REQUIRED
FOR THE COMPLETE KIT LESS PARTS LISTED ALL SOCKETS
INCLUDEO.

VISA or MASTERCHARGE Send account number, interbank
number, expiration date and sign your order. Approx, postage
will be added. Check or money order will be sent post paid in
U S. If you are not a regular customer, please use charge,
cashier's check or postal money order Otherwise there will
be a two-week delay for checks to clear. Calif, residents add
6% tax. Money back 30 day guarantee We cannot accept re-
turned IC's that have been soldered to. Prices subject to
change without notice $10 minimum order. $1.50 service charge
on orders less than $10.00.

Reader Service— see page 227

Microcomputing January 1980 217

AIM 65

BY ROCKWELL INTERNATIONAL

AIM 65 is fully assembled, tested and warranted. With the
addition of a low cost, readily available power supply, it’s
ready to start working for you.

AIM 65 features on-board thermal printer and
alphanumeric display, and a terminal-style keyboard. It
has an addressing capability up to 65K bytes, and comes
with a user-dedicated IK or 4K RAM. Two installed 4K
ROMS hold a powerful Advanced Interface Monitor
program, and three spare sockets are included to expand
on-board ROM or PROM up to 20K bytes.

An Application Connector provides for attaching a TTY
and one or two audio cassette recorders, and gives exter-
nal access to the user-dedicated general purpose I/O lines.

Also included as standard are a comprehensive AIM 65
User’s Manual, a handy pocket reference card, an R6500
Hardware Manual, an R6500 Programming Manual and an
AIM 65 schematic.

AIM 65 is packaged on two compact modules. The
circuit module is 12 inches wide and 10 inches long, the
keyboard module is 12 inches wide and 4 inches long.

They are connected by a detachable cable.

THERMAL PRINTER

Most desired feature on low-cost microcomputer systems . . .

• Wide 20-column printout

• Versatile 5x7 dot matrix format

• Complete 64-character ASCII alphanumeric format

• Fast 120 lines per minute

• Quite thermal operation

• Proven reliability

FULL-SIZE ALPHANUMERIC KEYBOARD

Provides compatibility with system terminals . . .

• Standard 54 key, terminal-style layout

• 26 alphabetic characters

• 10 numeric characters

• 22 special characters

• 9 control functions

• 3 user-defined functions

TRUE ALPHANUMERIC DISPLAY

Provides legible and lengthy display . . .

• 20 characters wide

• 16-segment characters

• High contrast monolithic characters

• Complete 64-character ASCII alphanumeric format

PROVEN R6500 MICROCOMPUTER SYSTEM DEVICES

Reliable, high performance NMOS technology . . .

• R6502 Central Processing Unit (CPU), operating at 1
MHz. Has 65K address capability, 13 addressing modes
and true index capability. Simple but powerful 56
instructions.

• Read/Write Memory, using R2114 Static RAM devices.
Available in IK byte and 4K byte versions.

• 8K Monitor Program Memory, using R2332 Static ROM
devices. Has sockets to accept additional 2332 ROM or
2532 PROM devices, to expand on-board Program
memory up to 20K bytes.

• R6532 RAM-Input/Output-Timer (RIOT) combination
device. Multipurpose circuit for AIM 65 Monitor functions.

• Two R6522 Versatile Interface Adapter (VIA) devices,
which support AIM 65 and user functions. Each VIA has
two parallel and one serial 8-bit, bidirectional I/O ports,
two 2-bit peripheral handshake control lines and two
fully-programmable 16-bit interval timer/event counters.

BUILT-IN EXPANSION CAPABILITY

• 44-Pin Application Connector for peripheral add-ons

• 44-Pin Expansion Connector has full system bus

• Both connectors are KIM-1 compatible

TTY AND AUDIO CASSETTE INTERFACES

Standard interface to low-cost peripherals . . .

• 20 ma. current loop TTY interface

• Interface for two audio cassette recorders

• Two audio cassette formats: ASCII KIM-1 compatible
and binary, blocked file assembler compatible

ROM RESIDENT ADVANCED INTERACTIVE MONITOR

Advanced features found only on larger systems . . .

• Monitor-generated prompts

• Single keystroke commands

• Address independent data entry

• Debug aids

• Error messages

• Option and user interface linkage

ADVANCED INTERACTIVE MONITOR COMMANDS

• Major Function Entry

• Instruction Entry and Disassembly

• Display/Alter Registers and Memory

• Manipulate Breakpoints

• Control Instruction/Trace

• Control Peripheral Devices

• Call User-Defined Functions

• Comprehensive Text Editor

LOW COST PLUG-IN ROM OPTIONS

• 4K Assembler— symbolic, two-pass ,A65-oio $79.00

• 8K BASIC Interpreter A65020 $99.00

POWER SUPPLY SPECIFICATIONS

• +5 VDC ± 5% regulated @ 2.0 amps (max)

• +24 VDC ±15% unregulated @ 2.5 amps (peak)

0.5 amps average

PRICE: $369.00 (IK RAM) $419.00 (4K RAM)

Plus $4.00 UPS (shipped in U.S. must give street address),
$10 parcel post to APO’s, FPO’s, Alaska, Hawaii, Canada,
$25 air mail to all other countries

AIM 65 USER MANUAL $5.00 plus $1.50 shipping & handling.

We manufacture a complete line of high quality expansion
boards. Use reader service card to be added to our mailing
list, or U.S. residents send $1.00 (International send $3.00
U.S.) for airmail delivery of our complete catalog.

ENTERPRIS

INCORPORATED

E S

2967 W. Fairmount Avenue
Phoenix AZ 8501 7
(602)265-7564

^R20

Start Computing For Just $129.95 With An
8085-Based Professional Computer Kit—

Explorerf85

100% compatible with all 8080A and
8085 software & development tools!

No matter what your future computing plans may
be, Level “A ”—at $129.95— is your starting point.

Starting at just $129.95 for a Level “A ” operating system,
you can now build the exact computer you want. Explorer/ 85
can be your beginner's system, OEM controller, or IBM-
formatted 8" disk small business system. . .yet you're never
forced to spend a penny for a component or feature you don 't
want and you can expand in small, affordable steps !

Now, for just SI 29.95, you can own the first level of a fully
expandable computer with professional capabilities— a com-
puter which features the advanced Intel 8085 cpu, thereby
giving you immediate access to all software and development
tools that exist for both the 8085 and its 8080A predecessor
( they are 100% software compatible)— a. computer which
features onboard S-100 bus expansion— plus instant conver-
sion to mass storage disk memory with either 5-1/4” diskettes
or standard IBM-formatted 8” disks.

For just SI 29.95 (plus the cost of a power supply, keyboard/
terminal and RF modulator, if you don’t have them already),
Explorer/85 lets you begin computing on a significant level. . .
applying the principles discussed in leading computer maga-
zines. . .developing ‘‘state of the art” computer solutions for
both the industrial and leisure environment.

Level “A” Specifications

Explorer/85’s Level “A” system features the advanced Intel
8085 cpu, an 8355 ROM with 2k deluxe monitor/operating
system, and an 8155 ROM-l/O— all on a single motherboard
with room for RAM/ROM/PROM/EPROM and S-100 ex-
pansion, plus generous prototyping space.

(Level “A” makes a perfect OEM controller for industrial
applications and is available in a special Hex Version which
can be programmed using
the Netronics Hex Keypad/
Display.)

PC Board: glass epoxy, plated
through holes with solder mask
• I/O: provisions for 25-pin
(DB25) connector for terminal
serial I/O, which can also sup-
port a paper tape reader
...provision for 24-pin DIP
socket for hex keyboard/dis-
play. . .cassette tape recorder in-
put ... cassette tape recorder output .. .cassette tape control
output ... speaker output... LED output indicator on SOD
(serial output) line. . .printer interface (less drivers). . .total of
four 8-bit plus one 6-bit I/O ports •Crystal Frequency: 6.144
MHz • Control Switches: reset and user (RST 7.5)
interrupt. . .additional provisions for RST 5.5, 6.5 and TRAP
interrupts onboard • Counter/ Timer: programmable, 14-bit
binary • System RAM: 256 bytes located at F800, ideal for
smaller systems and for use as an isolated stack area in
expanded systems. . . RAM expandable to 64k via S-100 bus or
4K on motherboard.

System Monitor (Terminal Version): 2k bytes of deluxe
system monitor ROM located at F000 leaving 0000 free for user
RAM/ROM. Features include tape load with labeling . . .tape
dump with labeling. . .examine/change contents of memory
...insert data... warm start. . .examine and change all
registers. . single step with register display at each break point,
a debugging/training feature... go to execution address...
move blocks of memory from one location to another. . .fill
blocks of memory with a constant. . .display blocks of memory
. . .automatic baud rate selection. . .variable display line length
control (1-255 characters/line). . .channelized I/O monitor
routine with 8-bit parallel output for high speed printer...
serial console in and console out channel so that monitor can
communicate with I/O ports.

System Monitor (Hex Version): Tape load with labeling. . .
tape dump with labeling. . .examine/change contents of mem-
ory... insert data... warm start .. .examine and change all

By Netronics

*«*»-

Level “A” at $129.95 is a
complete operating system,
perfect for beginners, hob-
biests, or industrial con-
troller use.

\%

Hex Keypad /Display.

Netronics R&FluT, Sept" i£T “ “ ™
333 Litchfield Road. New Milford, CT 06776

Please send the items checked below—

□ Explorer/85 Level “A” Kit (ASCII
Version), $129.95 plus $3 p&h.

□ Explorer/85 Level “A” Kit (Hex
Version), $129.95 plus $3 p&h.

□ 8k Microsoft BASIC on cassette
tape, $64.95 postpaid.

□ 8k Microsoft BASIC in ROM Kit
(requires Levels “B,” ”D,” and ”E”),

$99.95 plus $2 p&h.

□ Level “B” (S-100) Kit, $49.95 plus
$2 p&h.

□ Level “C” (S-100 6-card expander)

Kit, $39.95 plus $2 p&h.

□ Level "D” (4k RAM) Kit, $69.95

plus $2 p&h.

□ Level "E” (EPROM/ROM) Kit,

$5.95 plus 50C p&h.

□ Deluxe Steel Cabinet for Explorer/

85, $49. 95 plus $3 p&h.

□ ASCII Keyboard/Computer Ter-
minal Kit (features a full 128 character
set, upper & lower case, full cursor con-
trol, 75 ohm video output convertible
to baudot output, selectable baud rate,

RS232 C or 20 ma. I/O, 32 or 64 char-
acter by 16 line formats, and can be
used with either a CRT monitor or a TV
set (if you have an RF modulator),

$149.95 plus $2.50 p&h.

registers. . .single step with register display at each break point
...go to execution address. Level “A” in the Hex Version
makes a perfect controller for industrial applications and can
be programmed using the Netronics Hex Keypad/Display.

*•— Hex Keypad/Display
Specifications

Calculator type keypad with 24
system defined and 16 user
defined keys. 6 digit calculator
type display which displays full
address plus data as well as
register and status information.

Level “B” Specifications

Level‘‘B” provides the S-100 signals plus buffers/drivers to
support up to six S-100 bus boards and includes: address
decoding for onboard 4k RAM expansion select-able in
4k blocks. . address decoding for onboard 8k EPROM expan-
sion selectable in 8k blocks. . .address and data bus drivers for
onboard expansion . . . wait state generator (jumper selectable),
to allow the use of slower memories. . .two separate 5 volt
regulators.

Level “C” Specifications

Level ”C” expands Explorer’s
motherboard with a card cage,
allowing you to plug up to six
S-100 cards directly into the
motherboard. Both cage and
Explorer/85 with LQVQl cards arc neatly contained inside
”C” card cage. Explorer’s deluxe steel cabinet.

Level “C” includes a sheet metal superstructure, a 5-card gold
plated S-100 extension PC board which plugs into the mother-
board. Just add required number of S-100 connectors
Level “D” Specifications

Level “D” provides 4k or RAM, power supply regulation,
filtering decoupling components and sockets to expand your
F.xplorer/85 memory to 4k (plus the original 256 bytes located
in the 8 155 A). The static RAM can be located anywhere from
0000 to EFFF in 4k blocks.

Level “E” Specifications

Level “E” adds sockets for 8k of EPROM to use the popular
Intel 2716 or the TI 2516. It includes all sockets, power supply
regulator, heat sink, filtering and decoupling components.
Sockets may also be used for soon to be available RAM IC’s
(allowing for up to 12k of onboard RAM).

Order A Coordinated
Explorer/85 Applications Pak!

Experimenter’s Pak (SAVE $12.50)— Buy Level “A” and Hex
Keypad/Display for $199.90 and get FREE Intel 8085 user’s
manual plus FREE postage & handling!

Student Pak (SAVE $24.45)— Buy Level “A,” ASCII Key-
board/Computer Terminal, and Power Supply for $319.85 and
get FREE RF Modulator plus FREE Intel 8085 user’s manual
plus FREE postage & handling!

Engineering Pak (SAVE $41.00)— Buy Levels “A,” *‘B,”
“C,” ”D,” and ”E” with Power Supply, ASCII Keyboard/
Computer Terminal, and six S-100 Bus Connectors for $514.75
and get 10 FREE computer grade cassette tapes plus FREE
8085 user’s manual plus FREE postage & handling!

Business Pak (SAVE $89.95)— Buy Explorer/85 Levels “A,”
“B,” and “C” (with cabinet), Power Supply, ASCII Key-
board/Computer Terminal (with cabinet), 16k RAM, 12”
Video Monitor, North Star 5-1/4” Disk Drive (includes North
Star BASIC) with power supply and cabinet, all for just
$1599.40 and get 10 FREE 5-1/4” minidiskettes ($49.95 value)
plus FREE 8085 user’s manual plus FREE postage & handling!

Continental U S. A. Credit Card Buyers Outside Connecticut

CALL TOLL FREE 800-243-7428

To Order From Connecticut Or For Technical
Assistance, Etc. Call (203) 354-9375 “

plus $2 p&h.

□ Deluxe Steel Cabinet for ASCII
Keyboard/Terminal, $19.95 plus $2.50
p&h.

□ Power Supply Kit ( ± 8V @ 5 amps)
in deluxe steel cabinet, $39.95 plus $2
p&h.

□ Gold Plated S-100 Bus Connectors,
$4.85 each, postpaid.

□ RF Modulator Kit (allows you to
use your TV set as a monitor), $8.95
postpaid.

□ 16k RAM Kit (S-100 Board expands
to 64k), $199.95 plus $2 p&h.

□ 32k RAM Kit, $329.95 plus $2 p&h.

□ 48K RAM Kit, $459.95 plus $2 p&h.

□ 64k RAM Kit, $589.95 plus $2 p&h.

□ 16k RAM Expansion Kit (to expand
any of the above up to 64k), $139.95
plus $2 p&h each.

□ Intel 8085 cpu User’s Manual, $7.50

postpaid.

□ Special Computer Grade Cassette
Tapes, $1 .90 each or 3 for $5, postpaid.
D 12” Video Monitor (10 MHz band-
width), $139.95 plus $5 p&h.

□ North Star Double Density Floppy
Disk Kit (One Drive) for Explorer/
85 (includes 3 drive S-100 controller,

sonalized disk operating system— just i
plug it in and you’re up and running!),!
$699.95 plus $5 p&h.

□ Power Supply Kit for North Star!
Disk Drive, $39.95 plus $2 p&h.

□ Deluxe Case for North Star Disk!
Drive, $39.95 plus $2 p&h.

□ Experimenter’s Pak (see above),!
$199.90 postpaid.

□ Student Pak (see above), $319,851
postpaid.

□ Engineering Pak (see above), |
$514.75 postpaid.

□ Business Pak (see above), $1599.40 1
postpaid.

□ M.O./Cashier’s |
□ Master Charge |

Total Enclosed $

S )onn. res. add sales tax) By
Personal Check
Check □ Visa

(Bank It

Acct.# _
Signature _
Print

Name

_Exp. Date _

Address .

City_

L * j/iua «J>4* pOUl . ^ kj > w VUilUUllVl 9

□ Hex Keypad/Display Kit, $69.95 DOS - and extended BASIC with per- State

-Zip_

Send Me Information i

By Netronics

ASCII/BAUDOT,
STAND ALONE

Computer SgiU
Terminal 1W

The Netronics ASCII/BAUDOT Computer Terminal Kit is a
microprocessor-controlled, stand alone kcyboard/terminal
requring no computer memory or software. It allows the use of
either a 64. or 32 character by 16 line professional display for-
mat with selectable baud rate, RS232-C or 20 ma. output, full
cursor control and 75 ohm composite video output.

The keyboard follows the standard typewriter configuration
and generates the entire 128 character ASCII upper/lower case
set with 96 printable characters. Features include onboard
regulators, selectable parity, shift lock key, alpha lock jumper,
a drive capability of one TTY load, and the ability to mate
directly with almost any computer, including the new Ex-
plorer/85 and ELF products by Netronics.

The Computer Terminal requires no I/O mapping and
includes lk of memory, character generator, 2 key rollover,
processor controlled cursor control, parallel ASCII/BAUDOT
to serial conversion and serial to video processing— fully
crystal controlled for superb accuracy. PC boards are the
highest quality glass epoxy for the ultimate in reliability and
long life.

VIDEO DISPLAY SPECIFICATIONS

The heart of the Netronics Computer Terminal is the micro-
processor-controlled Netronics Video Display Board (VID)
which allows the terminal to utilize either a parallel ASCII or
BAUDOT signal source. The VID converts the parallel data to
serial data which is then formatted to either RS232-C or 20 ma.
current loop output, which can be connected to the serial I/O
on your computer or other interface, i.e., Modem.

When connected to a computer, the computer must echo the
character received. This data is received by the VID which
processes the information, converting to data to video suitable
to be displayed on a TV set {using an RF modulator) or on a
video monitor. The VID generates the cursor, horizontal and
vertical sync pulses and performs the housekeeping relative to
which character and where it is to be displayed on the screen.
Video Output: 1.5 P/Pinto 75 ohm (EIA RS-170) • Baud Rate:
110 and 300 ASCII • Outputs: RS232-C or 20 ma. current loop
• ASCII Character Set: 128 printable characters—

aBTg«0vxpvfWoaoi« O4 i^XI^

!"W*t / O**,-./0123456789:;< s >?

WBCDEFQUJKUWOP^^

v abcdtf9kijnftnowrst^vuxg{ , .) -»i

BAUDOT Character Set: A BCDEFGHIJKLMNOPQ
RSTUVWXYZ-?: * 3 $ ft ( ) . ,9014! 57; 2/68*
Cursor Modes: Home, Backspace, Horizontal Tab, Line Feed,
Vertical Tab, Carriage Return. Two special cursor sequences
are provided for absolute and relative X-Y cursor addressing •
Cursor Control: Erase, End of Line, Erase of Screen, Form
Feed, Delete • Monitor Operation: 50 or 60Hz (jumper
selectable.

Continental U.S.A. Credit Card Buyers Outside Connecticut

CALL TOLL FREE 800-243-7428

_ To Order From Connecticut Or For Technical ^ __
■ Assistance, Etc. Call (203) 354-9375 ■

I Netronics R&D Ltd., Dept. K-l
333 Litchfield Road, New Milford, CT 06776
I Please send the items checked below —

| □ Netronics Stand Alone ASCII Keyboard/Computer ■
Terminal Kit, $149.95 plus $3.00 postage & handling. |
Deluxe Steel Cabinet for Netronics Keyboard/Termi- ■
nal In Blue/Black Finish, $19.95 plus $2.50 postage I
and handling.

Video Display Board Kit alone (less keyboard), $89.95 I
plus $3 postage & handling.

12” Video Monitor (10 MHz bandwidth) fully assem- I

I bled and tested, $139.95 plus $5 postage and handling. !
□ RF Modulator Kit (to use your TV set for a monitor), I

I $8.95 postpaid.

□ 5 amp Power Supply Kit In Deluxe Steel Cabinet I
(± 8VDC @ 5 amps, plus 6-8 VAC), S39.95 plus $2 J
postage & handling.

I Total Enclosed (Conn. res. add sales tax) $ _

| By-

| □ Personal Check □ Cashiers Check/Money Order j

| □ Visa □ Master Charge (Bank ft ) |

I Acct. If |

l

r

1°
I □

I

!i

I

m Signature.

I Print
| Name

| Address _

_Exp. Date _

City_

_Zip

□ Send Me More Information Jj

V 0 Reader Service — see page 227

Microcomputing January 1980 219

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Be sure to include check or detailed credit card information.

Microcomputing January 1980 221

kb microcomputing book nook

• HOBBY COMPUTERS ARE HERE!-BK7322-lf you want to
come up to speed on how computers work . . . hardware and soft-
ware . . . this is an excellent book. It starts with the fundamentals
and explains the circuits, the basics of programming, along with a
couple of TVT construction projects, ASCII-Baudot, etc. This book
has the highest recommendations as a teaching aid for
newcomers. $4.95.*

• THE NEW HOBBY COMPUTERS— BK7340— This book takes it
from where Hobby Computers Are Here! leaves off, with chapters
on Large Scale Integration, how to choose a microprocessor chip,
an introduction to programming, low cost I/O for a computer, com-
puter arithmetic, checking memory boards, a Baudot monitor/edi-
tor system, an audible logic probe for finding those tough prob-
lems, a ham’s computer, a computer QSO machine . . . and much,
much more! $4.95*

• INTRODUCTION TO MICROPROCESSORS-BK1032-by

Charles Rockwell of MICROLOG, is an ideal reference for the indi-
vidual desiring to understand the hardware aspects of micropro-
cessor systems. Describes the hardware details of computer de-
vices in terms the beginner can understand, instead of treating the
micro chip as a “black box.” Specific systems are not described
and programming is only briefly discussed. $17.50 U.S. and
Canada; $20 elsewhere.*

• BASIC NEW 2ND EDITION— BK1081— by Bob Albrecht. Self-teaching guide to the computer language you will need to know
for use with your microcomputer. This is one of the easiest ways to learn computer programming. $5.95.*

• SCIENTIFIC RESEARCH INSTRUMENT’S BASIC SOFTWARE LIBRARY is a complete do-it-yourself kit, written in everybody’s
BASIC, immediately executable in ANY computer with 8K; no other peripherals needed. Volume I contains business and recrea-
tional programs and is 300 pages. Volume II is 260 pages and contains math, engineering, statistics and plotting programs.
Volume III contains money managing, advanced business programs such as billing, A/R, inventory, payroll, etc. Volume IV con-
tains general purpose programs such as loans, rates, retirement, plus games: Poker, Enterprise (take charge while Capt. Kirk is
away), Football and more! Volume V is filled with experimenters’ programs, including games, pictures and misc. problems such
as “logic.” Volume VI is a miniature business system; and Volume VII contains professional programs. Volume I — LB1002 - &
Volume II -LB1003 -$24.95* each, Volume III - LB1004- $39.95*, Volume IV- LB1005- & Volume V- LB1006 -$9.95* each,
Volume VI - LB1 005 - $49.95* , Volume VI I - LB1 008 - 39.95. *

• MICROPROCESSOR INTERFACING TECHNIQUES— BK1037— by Austin Lesea & Rodnay Zaks will teach you how to inter-
connect a complete system and interface it to all the usual peripherals. It covers hardware and software skills and techniques,
including the use and design of model buses such as the IEEE 488 or S100. $13.95.*

WHAT TO DO
AFTER YOU HIT
RETURN

P.C.C.’s First Book of
Computer Games

•mimiter

urn?*

• TTL COOKBOOK — BK1063 — by Donald Lancaster. Explains
what TTL is, how it works, and how to use it. Discusses practical
applications, such as a digital counter and display system, events
counter, electronic stopwatch, digital voltmeter and a digital tach-
ometer. $9.50.

• CMOS COOKBOOK- BK1011 —by Don Lancaster. Details the
application of CMOS, the low power logic family suitable for most
applications presently dominated by TTL. Required reading for
every serious digital experimenter! $10.50.*

• TVT COOKBOOK— BK1064— by Don Lancaster. Describes the
use of a standard television receiver as a microprocessor CRT ter-
minal. Explains and describes character generation, cursor con-
trol and interface information in typical, easy-to-understand Lan-
caster style. $9.95.*

• THE “COMPULATOR” BOOK-BUILDING SUPER
CALCULATORS & MINICOMPUTER HARDWARE WITH
CALCULATOR CHIPS— BK1012— by R.P. Haviland, provides
ideas, design info and/or printed circuit boards for calculator chip
projects such as tape control of calculator electronic lock, dial-a-
telephone, etc. $7.95.*

• BASIC COMPUTER GAMES— BK1 074— Okay, so once you get your computer and are running in BASIC, then what? Then you
need some programs in BASIC, that’s what. This book has 101 games for you from very simple to real buggers. You get the
games, a description of the games, the listing to put in your computer and a sample run to show you how they work. Fun. Any
one game will be worth more than the price of the book for the fun you and your family will have with it. $7.50.*

• WHAT TO DO AFTER YOU HIT RETURN — BK1071 — PCC’s first book of computer games ... 48 different computer games
you can play in BASIC . . . programs, descriptions, many illustrations. Lunar Landing, Hammurabi, King, Civel 2, Qubic 5, Tax-
man, Star Trek, Crash, Market, etc. $10.95.*

• MICROCOMPUTING CODING SHEETS Microcomputing’s dozen or so programmers wouldn’t try to work without these
handy scratch pads, which help prevent the little errors that can cost hours and hours of programming time. Available for pro-
gramming is Assembly/Machine Language (PD1001), which has columns for address, instruction (3 bytes), source code (label,
op code, operand) and comments; and for BASIC (PD1002) which is 72 columns wide. 50 sheets to a pad. $2.39.*

•Use the order card in the back of this magazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 handling.

FOR TOLL FREE ORDERING CALL 1-800-258-5473

kb microcomputing book nook

• PROGRAMMING IN PASCAL— BK1 1 40-by Peter Grogono. The
computer programming language PASCAL was the first language
to embody in a coherent way the concepts of structured program-
ming, which has been defined by Edsger Dijkstra and C.A.R.

Hoare. As such, it is a landmark in the development of program-
ming languages. PASCAL was developed by Niklaus Wirth in
Zurich; it is derived from the language ALGOL 60 but is more
powerful and easier to use. PASCAL is now widely accepted as a
useful language that can be efficiently implemented, and as an ex-
cellent teaching tool. It does not assume knowledge of any other
programming language; it is therefore suitable for an introductory
course. $9.95.*

• MICROPROCESSOR LEXICON -ACRONYMS AND DEFINI-
TIONS - BK1 137 - compiled by the staff of SYBEX, is a convenient
reference in pocket-size format. Sections include acronyms and
definitions, part numbers and their definitions, S-100 signals;

RS232 signals, IEEE 499 signals, microcomputers and micropro-
cessors, JETDS summary (military) and a code conversion table.

$2.95.*

• INSTANT BASIC -BK1 131 -by Jerald R. Brown. For the per-
sonal computer enthusiast or the user of DEC’S BASIC PLUS lan-
guage, here is a new book to teach you BASIC. It teaches BASIC to
beginners using interesting programming ideas and applications
that will be easily understood by the home computer programmer.

BASIC PLUS users know that the two languages are very similar,
so this book can be used by them as well. This is an “active par-
ticipation” workbook, designed to be used with your home com-
puter so you can learn by doing! Ideas are slowly introduced in a
nonmathematical context so the beginner can quickly learn good
programming techniques. $6.00.*

• MY COMPUTER LIKES ME .. . WHEN I SPEAK BASIC-BK1039-An introduction to BASIC . . . simple enough for kids. If you
want to teach BASIC to anyone quickly, this is the way to go. $2.00.*

• COMPUTER PROGRAMMING HANDBOOK— BK1014— by Peter Stark. A complete guide to computer programming and data
processing. Includes many worked-out examples and history of computers. $9.95.*

• MICROCOMPUTER DICTIONARY— BK1034— This microcomputer dictionary fills the need to become quickly acquainted
with the terminology and nomenclature of the revolution in computers. There is also a comprehensive electronics/computer
abbreviations and acronyms section. $15.95.*

• YOUR HOME COMPUTER— BK1172— by James White, is an in-
troduction to the world of personal microcomputing. This book
tells you everything you want to know about home computing and
gives the computer novice a painless introduction to microcom-
puter technology and terminology, beginning with what com-
puters are and how they work. This basic book requires no prior
knowledge or experience in electronics or computing. It provides
information about home computer kits; guidelines for selecting
and building your own microcomputer, how to use your home com-
puter and what you can do with it; lists of computer stores, clubs,
periodicals; and answers to many more of your questions about
microcomputers and the jargon surrounding the personal comput-
ing scene today. $6.00.*

• HOW TO BUILD A MICROCOMPUTER— AND REALLY UNDER-
STAND IT— BK7325— by Sam Creason. The electronics hobbyist
who wants to build his own microcomputer system now has a prac-
tical “How-To” guidebook. This book is a combination technical
manual and programming guide that takes the hobbyist step-by-
step through the design, construction, testing and debugging of a
complete microcomputer system. Must reading for anyone desir-
ing a true understanding of small computer systems. $9.95.*

THE BASIC HANDBOOK— BK1 174— by David Lien. This book is
unique. It is a virtual ENCYCLOPEDIA of BASIC. While not favoring
one computer over another, it explains over 250 BASIC words, how
to use them and alternate strategies. If a computer does not
possess the capabilities of a needed or specified word, there are
often ways to accomplish the same function by using another
word or combination of words. That’s where the HANDBOOK
comes in. It helps you get the most from your computer, be it a
“bottom-of-the-line” micro or an oversized monster. $14.95.*

• MICROCOMPUTER PRIMER— BK1035— by M. Waite and M. Pardee. Describes basic computer theory, explains numbering
systems and introduces the reader to the world of programming. Describes the world of microcomputing in “real world” termi-
nology. $7.95.*

• THE STORY OF COMPUTERS — BK1056 — by Donald D. Spencer, is to computer books what Dick and Jane is to novels . . .
elementary, gives the non-computerist a fair idea of what the hobbyist is talking about when he speaks computer lingo. At-
tempts to explain what computers are and can do to a spouse, child or any non-electronics-minded friend. $4.95.*

‘Use the order card in the back of this magazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 handling.

FOR CUSTOMER SERVICE CALL 603-924-7298

kb microcomputing bookjx

PIMS

Personal Information
Management System

• PROGRAMMING THE 6502- BK1 005- Rodnay Zaks has de-
signed a self-contained text to learn programming, using the
6502. It can be used by a person who has never programmed
before, and should be of value to anyone using the 6502. The
many exercises will allow you to test yourself and practice the
concepts presented. $11.95*

• 6502 APPLICATIONS BOOK— BK1006— Rodnay Zaks pre-
sents practical-application techniques for the 6502
microprocessor, assuming an elementary knowledge of micro-
processor programming. You will build and design your own
domestic-use systems and peripherals. Self-test exercises in-
cluded. $12.95*

• HOW TO SELL ANYTHING TO ANYBODY— BK7306— According to The Guiness Book of World Records , the author, Joe Girard,
is “the world’s greatest salesman.” This book reveals how he made a fortune— and how you can, too. $2.25.*

• PIMS: PERSONAL INFORMATION MANAGEMENT SYSTEM— BK1009— Learn how to unleash the power of a personal com-
puter for your own benefit in this ready-to-use data-base management program. $9.95.*

• LOW-COST, PERSONAL COMPUTER-BASED INVESTMENT
DECISION SYSTEMS -BK1 101 -Use this guidebook by Man-
Computer Systems, Inc.’s president, Jerry Felsen, to develop in-
expensive personal computer systems that can help you make
better investment decisions. $15.00.*

• 6800 SOFTWARE GOURMET GUIDE AND COOKBOOK—

BK1075— Like its culinary cousin, The 8080 Gourmet Guide , this
new book by Scelbi Computing and Robert Findley describes
sorting, searching and other routines— this time for the 6800
user. $10.95.*

• 8080 SOFTWARE GOURMET GUIDE AND COOKBOOK-

BK1 1 02 — If you have been spending too much time developing
simple routines for your 8080, try this new book by Scelbi Com-
puting and Robert Findley. Describes sorting, searching, and
many other routines for the 8080 user. $10.95.*

• HOW TO MAKE MONEY WITH COMPUTERS- BK1003- In 10
information-packed chapters, Jerry Felsen describes more than
30 computer-related, money-making, high profit, low capital in-
vestment opportunities. $15.00.*

• ADD ’N STAC— BX1003— If you’ve got programs lying around
and want them organized in easy-to-locate fashion Add ’N Stac is
the answer. Each unit stores eight cassettes. Each module locks
together with the next and grows with your collection. Build
yourself a software library with Add ’N Stac by ordering from the
Book Nook. As your library grows you’ll need more of these
handy units so order more than one today. Several colors are
available and you can mount them to your wall, desk, table or
keep them loose for taking with you. Colors and prices are:

Smoke $3.00*; Black, Dark Blue, Orange, Brown, White, Red
$2.50.*

*Use the order card in the back of this maaazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 handling.

FOR TOLL FREE ORDERING CALL 1-800-258-5473

kb microcomputing book nook

• ADVANCED BASIC- BK1000- Applica-
tions and problems by James Coan is for
those who want to extend their expertise
with BASIC. Offers advanced techniques
and applications. $15.00.*

• PAYROLL WITH COST ACCOUNTING -
IN BASIC -BK1001 -by L. Poole & M.
Borchers, includes program listings with
remarks, descriptions, discussions of the
principle behind each program, file
layouts, and a complete user’s manual
with step-by-step instructions, flowcharts,
and simple reports and CRT displays.
Payroll and cost accounting features in-
clude separate payrolls for up to 10 com-
panies, time-tested interactive data entry,
easy correction of data entry errors, job
costing (labor distribution), check printing
with full deduction and pay detail, and 16
different printed reports, including W-2
and 941. $15.00.*

• SOME COMMON BASIC PROGRAMS-

BK1053— published by Adam Osborne &
Associates, Inc. Perfect for non-technical
computerists requiring ready-to-use pro-
grams. Business programs, plus miscel-
laneous programs. Invaluable for the user
who is not an experienced programmer. All
will operate in the stand-alone mode. $9.50
paperback.*

• THE SECRET GUIDE TO COMPUTERS

Parts 1, 2 and 3 by Russ Walter. Part One
describes computers in general, and after
reading for ten minutes you will be writing
simple BASIC programs! Part Two dis-
cusses computer applications. It’s one
thing to master the syntax of the language
such as BASIC and another to solve prob-
lems using the new tool. Part Three
describes programming languages. Ever
heard of APL and QLISP? BASIC is not the
only language used to program comput-
ers. 7th Edition. Part I — BK1050— $2.75*;
Part II — BK1051— $2.50*; Part III — BK1052
-$3.50.*

*Use the order card in the back of this magazine or itemize your order on a separate piece of paper and mail to:

Kilobaud Microcomputing Book Department • Peterborough NH 03458. Be sure to include check or detailed credit card information.

All orders, add $1.00 handling.

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MICROCOMPUTING

Peterborough NH 03458

T.M.

J

• AN INTRODUCTION TO MICROCOM-
PUTERS, VOL. 0— BK1130— The Begin-
ner’s Book— Written for readers who know
nothing about computers— for those who
have an interest in how to use computers
—and for everyone else who must live with
computers and should know a little about
them.Thefirst in aseries of 4 volumes, this
book will explain how computers work and
what they can do. Computers have be-
come an integral part of life and society.
During any given day you are affected by
computers, so start learning more about
them with Volume 0. $7.95.*

• VOL. I -BK1030- Dedicated to the
basic concepts of microcomputers and
hardware theory. The purpose of Volume I
is to give you a thorough understanding of
what microcomputers are. From basic
concepts (which are covered in detail),
Volume I builds the necessary compo-
nents of a microcomputer system. This
book highlights the difference between
minicomputers and microcomputers.
$8.50.*

• VOL. II— BK1031 (loose leaf)— $25.00*;
BK1040 (with binder)— $30.00*— Contains
descriptions of individual microproces-
sors and support devices used only with
the parent microprocessor. Volume II
describes all available chips.

• VOL. Ill — BK1132 (loose leaf)— $15.00*;
BK1133 (with binder)— $20.00.* Contains
descriptions of all support devices that
can be used with any microprocessor.

• FUN WITH COMPUTERS AND BASIC—
BK1021 — by Donald D. Spencer, contains
an easy-to-understand explanation of the
BASIC Programming Language and is in-
tended for persons who have had no pre-
vious exposure to computer programming.
Over half the book is devoted to problems
using games, puzzles, and mathematical
recreations. A superior book for self-
teaching and learning computer program-
ming. $6.95.*

FOR CUSTOMER SERVICE CALL 603-924-7298

kilobaud

MICROCOMPUTING ™ LIST OF 4DMERTISERS

A90 Aardvark Technical Serv 96, 161

A112 The Abacus 114

A88 A B Computers 161

A75 ACS Service. . . . 82, 129

A38 Advanced Comp. Products 207

A102 Adventure International 156

A101 Alpha Byte Storage 184, 190

A111 Alphanetics 139

A66 American Square Computers. . 194

A98 Bill Archbold 96

A1 14 Atari Personal Comp. Sys 4

All 5 Audio Video Systems 190

A71 Automated Simulations 31

B50 Bluebird’s Inc 141

B33 The Bottom Shelf, Inc 93, 133

Cl 28 Cecdat, Inc 30, 179

C170 Centuri, Recording Studio, Inc.

184

Cl 60 CFR Associates 194

C116 CGRS Microtech 184

Cl 72 Checks To Go 73

Cl 59 Compro 166

Cl 22 CompuCover 178

C109 CompuSoft Publishing 177

Cl 73 Compute 158

C171 Computer Center 190

C108 Computer City 113

Cl 67 Computer Concepts 139

C64 Computer Corner of NJ 184

C175 Computer Data Services 192

Cl 56 Computer Design Labs 97

C111 Computer Forum 142

C104 Computer Information Exchg.

156

Cl 68 Computer Shopper 119

C147 The Computer Stop 155

C174 Computer Specialties 178

C86 Computrex 63

Cl 14 Computronics 55

Cl 08 The CPU Shop 113

Cl 69 Creative Computing 109

Cl 23 Cuddly Software 139

C132 Custom Electronics, Inc 184

Cybernetics, Inc 156

D43 Dr. Daley 168

D50 Data/Print 89,167

D40 Datasearch 142

D65 Datasouth Computer Corp 156

D72 D C software & Comp. Products

166

D61 Delta Systems 185

D28 Deltroniks 194

D47 Designco 186

D70 D-G Electronic Developments Co.

20

D63 Digital Marketing 61

Digital Research Computers. . . 212

Digital Research Parts 175

D60 Digital Video Systems 192

D69 Disco-Tech 188

D71 D & R Creative Sys 190

D67 Dwo Quong Fok Lok Sow 154

E34 Ecosoft 118

E37 80-Us Journal 143

E18 Electravalue Industrial 190

E36 Electronics Specialists, Inc 161

E21 Electronics Systems 198, 199

E56 Essex Publishing Co 192

E48 Exatron 81

F20 Fuller Software 101

G34 Allen Gelder 194

G28 Gimix, Inc 162

G4 Godbout Electronics 216

H49 Heath Co 73

H25 Hobby World 195

H45 Houston Micro-Computer Tech.,

Inc 49

H47 Hubert Howe (Howe Software)

.. 156

147 Ian Electronics 161

124 Innovative Technology 192

132 Instant Software 120-125

113 Integrand 148

150 Interactive Microwave, Inc 169

149 Interactive Structures, Inc 22

121 Intertec Data Systems 3, 20

* Ithaca Intersystems, Inc 35, 185

146 Iridis 88

J6 Jade Computer Prod 208, 209

J1 Jameco Electronics 214, 215

J13 J.E.S. Graphics 192

J12 JPC Products 186

K14 Key Electronics 138

L27 Lake City Technical Products

179

L3 Dr. Lee 101,189

L19 Level IV Products, Inc 187

* Lifeboat Associates 75, 189

L25 The Logic Store 184

Ml 24 MaCo Manufacturing 158

M77 Madhatter Software 83

M121 Management Informa. Spec. . . 192
Ml 19 Med Systems 114

Micro Applications Group. . . 30, 48
M82 Microcomputer Tech/Apparat

196

Ml 10 MicroDaSys 21,186

M116 Micro Discount Service 192

Ml 12 Micro Innovations 161

M73 Micromail 177

M95 Micro Management Systems. . 159

Ml 05 Micro Matrix 167

M126 Micromint 163

M115 Micron 101

Ml 25 Micro Phase Systems 190

M81 Micro Products Unltd 192

M67 Microsette 96, 138

M44 Micro Technology Unltd 20,80

Ml 08 Microtel, Inc 163

M127 Microwave Associates, Inc 179

M94 Mid East Micro 154

M106 Midwest Comp. Peripherals 179

M70 Midwest Scientific CIV

M39 Mikos 217

Ml 14 Miller Microcomputer Serv 161

M6 Mini Micro Mart 204, 205

M32 Mullen Computer Boards 131

M83 Multi-Business Comp. Sys 143

Mumford Micro Systems 48

* National Radio Institute 157

N12 NEECO 191

N15 Netronics R&D Ltd 139,219

N7 Newman Computer Exchg.

(CompuMart) 213

N29 North Star Synergistics 159

013 Ohio Scientific 10-13

05 OK Machine & Tool 149

018 Omnitek Systems 141, 192

02 On-Line 132

OIO Optimal Technology, Inc.

131, 155

014 Organic Software 189

08 Orthon Computers 96

09 Otto Electronics 155

P66 Pacific Exchanges 96

P9 PAIA 21, 167, 169

P63 Parasitic Engineering 168

P7 Percom Data Co., Inc Cl I

P82 Percom Data Co., Inc 23

P67-P71 Percom Data Co., Inc 24, 25

P83 Percom Data Co., Inc 188

P52 The Peripheral People 162

Cl 39 Personal Software CHI

P60 Practical Applications 155

P21 Priority One 200-202

P48 Programma International, Inc. . . 45

Q12 Quality Software 166

Q8 Quant Systems 88

Q9 Quasar Data Products 105

Q3 Quest Electronics 203

R24 Racet Computes 176

R11 Radio Hut 210

Radio Shack 197

R34 Radio Shack Authorized Sales

Center 131

Rainbow Computing, Inc 61

R8 Ramsey Electronics 162, 163

R33 Realty Software Co 187, 189

Recreational Program 89

R20 RNB Enterprises 218

R7 Rondure Company 193

SI 29 SC Digital 158

SI 6 Selectronics 206

SI 27 Lear Siegler/Data Products Div.

S121 Simutek 159

S1 13 Sirius Systems 34

S95 Small Business Computer Service

190

S51 Small Systems Software 41

S90 Softape 132

S123 Solaris Press 176

S128 Structured Program Designers

187

SI 26 Sun-Technology, Inc 22,185

S61 Supersoft 118

T37 TanoCorp .77

T57 Taranto & Associates 73

Til Tarbell Electronics 21

T74 Technology Marketing Analysis

Corp 59

T26 Telecommunications Serv 190

T56 TNWCorp 22,88, 184

T69 TYC Software 189

Tora Systems Limited 154

T41 Total Information Services 169

T75 Total Information Services 189

T46 Transition Enterprises, Inc 169

U14 UHF Associates 19

U12 Ultimate Computer Systems 96

V8 Vector Electronic Co. Inc 21

V28 VR Data Corporation 142, 143

Wallen Electronics 211

W22 Wameco, Inc 217

W20 WEB Associates 165

W29 West Side Electronics 132

W36 Will Serve Industries 114

W16 World Wide Electronics 138

X4 Xitex Corp 65

Y3 Your Own Computer, Ltd 190

From Kilobaud 67-69, 186, 220-226

From 80 Microcomputing 115

•Reader Service inquiries not honored. Please contact
advertiser directly.

226 Microcomputing January 1980

Solve your personal energy crisis.
Let VisiCalc Power do the work.

TM— VisiCalc is a trademark of
Personal Software, Inc.

With a calculator, pencil and paper you can spend hours plan-
ning, projecting, writing, estimating, calculating, revising, erasing
and recalculating as you work toward a decision.

Or with VisiCalc and your Apple* II you can explore many
more options with a fraction of the time and effort you've spent
before.

VisiCalc is a new breed of problem-solving software. Unlike
prepackaged software that forces you into a computerized
straight jacket, VisiCalc adapts itself to any numerical problem
you have. You enter numbers, alphabetic titles and formulas on
your keyboard. VisiCalc organizes and displays this infor-
mation on the screen. You don't have to spend your time
programming.

Your energy is better spent using the results than get-
ting them.

Say you're a business manager and want to project
your annual sales. Using the calculator, pencil and paper
method, you'd lay out 12 months across a sheet
and fill in lines and columns of figures on
products, outlets, salespeople, etc. You'd cal-
culate by hand the subtotals and summary
figures. Then you'd start revising, erasing
and recalculating. With VisiCalc, you simply
fill in the same figures on an electronic
"sheet of paper" and let the computer do
the work.

Once your first projection is complete,
you're ready to use VisiCalc's unique,
powerful recalculation feature. It lets you
ask "What if?7 examining new options
and planning for contingencies. "What if"
sales drop 20 percent in March? Just type in
the sales figure. VisiCalc instantly updates
all other figures affected by March sales.

Or say you're an engineer working on a design problem and are
wondering "What if that oscillation were damped by another 10
percent?" Or you're working on your family's expenses and
wonder "What will happen to our entertainment budget if the
heating bill goes up 15 percent this winter?" VisiCalc responds
instantly to show you all the consequences of any change.

Once you see VisiCalc in action, you'll think of many more
uses for its power. Ask your dealer for a demonstration and dis-
cover how VisiCalc can help you in your professional work and
personal life.

You might find that VisiCalc alone is reason enough to
own a personal computer.

VisiCalc is available now for Apple II computers with
versions for other personal computers coming soon. The
Apple II version costs just $99.50 and requires a 32k disk
system.

For the name and address of your nearest VisiCalc
dealer, call (408) 745-7841 or write to Personal
Software, Inc., Dept. K, 592 Weddell Dr.,
Sunnyvale, CA 94086. If your favorite
dealer doesn't already carry Personal
Software products, ask him to
give us a call.

VisiCalc was developed exclusively for
Personal Software by Software Arts, Inc.,
Cambridge, Mass.

gO r

'Apple is a registered trademark

Inventory Problems?

Are you hoving trouble keeping the right nuts
ond bolts in stock? Since even o simple mistake con
cost you time and money, a good inventory system
should do more than just count parts. It should tell
you exactly whot you need, when you need it,
where to get it, ond how much it will cost.

The MSI Inventory System Seven enables you to
maintain a versatile data base for controlling
inventory. It lists part number, description, quantity
on hand, vendor, cost, selling price, optional
pricing, usage levels for previous month, present
month, and year-to-date, and much more.

When quantity on hand items reach minimum
levels, the System Seven compiles an automatic
reorder list. This list can be generated by spe-
cific vendor as well as a complete listing of
all materials to be ordered.

In addition to the item listing, the In-
ventory System Seven "bill of materials"
provides you with a complete inventory
of items used in the manufacture of subassemblies
and complete products. It also contains other cost
items such as labor costs, total raw materials costs,
and miscellaneous costs.

inventory control fast and efficient. The System
Seven will interface with any industry standard CRT,
and you have the option of both a "daisy wheel"
word processor for high quality document prepa-
ration and a dot matrix printer for high speed
production.

The System Seven can be expanded to handle
all your data processing needs or you can select
one of nine other MSI systems now available
for business, industrial, scientific, educational, and
personal applications.

If you need more than just a nuts and bolts
inventory system, we have more informa-
tion about how the Inventory
System Seven can solve your pro
blems economically.

The MSI Inventory System Seven is built around
the versatile MSI 6800A Computer with 56K of
RAM. An integral dual mini-floppy memory gives
you on additional 630K of memory and makes

MSI Inventory System Seven

midwest Scientific

220 W. Cedar, Olathe, Kansas 66061,(913)764-3273
TWX 91 0 749 6403 (MSI OLAT), TELEX 42525 (MSI A OLAT)

Zl",